Do not delete or replace mskssrv.sys yet. Microsoft’s reviewed documentation does not identify this filename, so its identity is unverified. A safe fix starts by recording the exact stop code, checking the file’s complete path and digital signature, and determining whether the crash points to Windows component corruption, another driver, malware, or a failing disk.
The sequence below repairs Windows first, then addresses drivers and suspicious files without risking a blind deletion of a kernel file.
As an Amazon Associate I earn from qualifying purchases.
What mskssrv.sys is—and why its identity is uncertain
A file ending in .sys is a Windows system or kernel-mode driver file. When one is named on a blue screen, Windows has identified the file involved in the crash; that does not by itself prove the file is the original cause. A damaged component store, a conflicting driver, unsafe software, or storage errors can all produce the same symptom.
Recommended Free Tools
No reviewed Microsoft source gives mskssrv.sys an authoritative identity. Treat the filename as unverified until you inspect its location, signer, associated service or driver, and the stop code or event that mentioned it. A filename that appears outside the normal Windows driver directory or has an invalid signature is suspicious, but neither fact alone proves malware.
#1 Best Overall
- Dual USB-A & USB-C Bootable Drive – compatible with nearly all Windows PCs, laptops, and tablets (UEFI & Legacy BIOS). Works with Surface devices and all major brands.
- Fully Customizable USB – easily Add, Replace, or Upgrade any compatible bootable ISO app, installer, or utility (clear step-by-step instructions included).
- Complete Windows Repair Toolkit – includes tools to remove viruses, reset passwords, recover lost files, and fix boot errors like BOOTMGR or NTLDR missing.
- Reinstall or Upgrade Windows – perform a clean reinstall of Windows 7 (32bit and 64bit), 10, or 11 (amd64 + arm64) to restore performance and stability. (Windows license not included.). Includes Full Driver Pack – ensures hardware compatibility after installation. Automatically detects and installs drivers for most PCs.
- Premium Hardware & Reliable Support – built with high-quality flash chips for speed and longevity. TECH STORE ON provides responsive customer support within 24 hours.
Before changing anything
Record the crash evidence
- Write down the complete stop code shown on the blue screen, such as
DRIVER_IRQL_NOT_LESS_OR_EQUALor another code. If the screen disappears too quickly, check Event Viewer under Windows Logs > System and look for the time of the crash. - Record when the problem began and whether Windows, a graphics, audio, Wi-Fi, Bluetooth, USB, storage, or other driver was installed or updated immediately beforehand.
- Copy the full path shown for
mskssrv.sys. The path is more useful than the filename alone.
Back up important files
Copy irreplaceable documents, saved games, photographs, and other data to another drive or cloud storage before attempting repairs. If the computer is unstable, use another computer or boot into recovery tools to copy files. Do not start by renaming, replacing, or deleting the SYS file.
Inspect the file’s path, signature, and owner
Check the location and properties
- Open File Explorer and navigate to the recorded path.
- Right-click the file, choose Properties, and inspect the General, Details, and Digital Signatures tabs.
- Note the company or signer, signature status, product description, file version, and creation or modification dates. A Windows kernel driver is commonly stored below the Windows system driver directory, but that location does not prove the file is genuine.
- If the file is in a user-download folder, a temporary folder, a game folder, or another unexpected location, record that fact rather than deleting it immediately.
Map the file to a service or driver
Open Command Prompt as administrator and use the service and driver information available on your PC to identify the owner. You can list installed driver packages with pnputil /enum-drivers and inspect driver services with sc query type= driver. These commands may not display the filename directly, but they can reveal a recently installed package or service that matches the crash timing. Keep a copy of the output if you need to contact the hardware or software vendor.
Repair Windows components in the correct order
Microsoft recommends running Deployment Image Servicing and Management (DISM) before System File Checker. DISM repairs the Windows image and component store; SFC then checks protected system files and replaces corrupted copies from the local cache.
- Sign in to Windows with an administrator account. Search for Command Prompt, right-click it, and select Run as administrator.
- Run
DISM.exe /Online /Cleanup-image /Restorehealth. Leave the window open until it reaches completion. Interrupting the process can leave the repair unfinished. - After DISM completes, run
sfc /scannow. Microsoft describes this command as scanning protected system files and replacing corrupted files with a cached copy. - Read the final message. If SFC reports that it repaired files, restart Windows and check whether the blue screen returns. If it reports that it could not repair some files, save the result and continue with the recovery and driver checks below.
The order matters: running SFC first can leave it without a healthy component source. Neither command identifies an unknown third-party driver, so a clean result does not prove that mskssrv.sys is safe or that a hardware fault is absent.
If Windows will not start
Enter Windows Recovery Environment
Windows Recovery Environment (WinRE) provides Startup Repair, System Restore, Safe Mode, and Command Prompt when normal startup fails. If the built-in recovery partition is unavailable, a Windows installation or recovery USB can provide access to these tools; verify that the media matches your Windows edition and that you have a current backup.
Rank #2
- High-speed USB 3.0 performance of up to 150MB/s(1) [(1) Write to drive up to 15x faster than standard USB 2.0 drives (4MB/s); varies by drive capacity. Up to 150MB/s read speed. USB 3.0 port required. Based on internal testing; performance may be lower depending on host device, usage conditions, and other factors; 1MB=1,000,000 bytes]
- Transfer a full-length movie in less than 30 seconds(2) [(2) Based on 1.2GB MPEG-4 video transfer with USB 3.0 host device. Results may vary based on host device, file attributes and other factors]
- Transfer to drive up to 15 times faster than standard USB 2.0 drives(1)
- Sleek, durable metal casing
- Easy-to-use password protection for your private files(3) [(3)Password protection uses 128-bit AES encryption and is supported by Windows 7, Windows 8, Windows 10, and Mac OS X v10.9 plus; Software download required for Mac, visit the SanDisk SecureAccess support page]
- Turn on the PC and interrupt startup two or three times by holding the power button when the Windows logo appears. Windows should eventually display Preparing Automatic Repair and then Advanced options. If that does not work, boot from Windows installation or recovery media and choose Repair your computer.
- Select Troubleshoot > Advanced options.
- Choose Startup Repair first. Allow it to complete and restart once.
- If the problem began after a system or driver change, return to Advanced options and try System Restore using a restore point dated before the failure.
- Choose Startup Settings > Restart, then select Safe Mode or Safe Mode with Networking. Safe Mode loads a limited set of drivers, making it easier to remove a recently installed driver or run the Defender scan.
- Use Command Prompt in WinRE only when the graphical options fail. Drive letters can change in recovery mode, so confirm the Windows volume before running any offline operation.
Repair the driver connected to the crash
Use Device Manager
- In normal Windows or Safe Mode, right-click Start and open Device Manager.
- Expand the category suggested by the stop code or recent change, such as Display adapters, Sound, video and game controllers, Network adapters, Bluetooth, Universal Serial Bus controllers, or Storage controllers.
- Right-click the suspected device and choose Properties. On the Driver tab, record the provider, date, and version.
- Use Update driver and install a driver from the device manufacturer or Windows Update. If the crash began immediately after an update, choose Uninstall device, restart, and install a known-good package from the manufacturer. Do not remove unrelated devices merely because their names look unfamiliar.
After each driver change, restart and test the activity that previously caused the crash. Changing one device at a time makes it possible to identify the actual trigger and to reverse the last change if the symptoms worsen.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Check for malware without assuming the file is malicious
Use Microsoft Defender to scan the file and the surrounding system. A suspicious path or invalid signature justifies a scan and further investigation; it is not proof that the file is malware. Do not download a replacement .sys file from an untrusted archive, and do not allow a website’s “fix” utility to overwrite a kernel file before you know its owner.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problems- Open Windows Security > Virus & threat protection.
- Run a Full scan. If Windows is unstable, use Defender’s available offline scan from the same area, then restart.
- Quarantine only items Defender identifies. Keep the detection name and path so you can distinguish a real detection from the original crash report.
Choose the next step from the evidence
| Evidence | Most useful next action | Why |
|---|---|---|
| Windows boots; DISM or SFC reports corruption | Complete both repairs, restart, and retest | The Windows image or protected files may have been damaged. |
| Crash began after a graphics, audio, network, USB, storage, or other driver change | Update or uninstall that device’s driver in Device Manager | The timing points to a driver conflict or bad package. |
| File is outside the expected Windows driver location or has an invalid signature | Record the owner, run Microsoft Defender, and avoid deletion until identified | Those findings are suspicious but do not establish malware by themselves. |
| Windows will not boot | Use WinRE’s Startup Repair, System Restore, Safe Mode, or Command Prompt; use recovery media if needed | Offline tools can work when the installed Windows environment cannot. |
| Repeated crashes, disk errors, or unsigned kernel drivers | Escalate to the hardware or software vendor or a qualified technician | Continued failures may indicate storage damage, a low-level driver problem, or a deeper hardware fault. |
Can you delete mskssrv.sys?
Not safely based on the filename alone. If it is required by Windows or a legitimate driver, deletion can make the system unbootable. If Defender or the file’s verified owner identifies it as unwanted, remove it through the responsible application’s uninstaller or Defender’s quarantine process instead of manually deleting the file. If you have a verified backup or restore point, use that recovery path rather than substituting a SYS file downloaded from an archive.
When to stop troubleshooting yourself
- The PC cannot enter WinRE, Safe Mode, or recovery media.
- Blue screens continue after DISM, SFC, and removal or update of the suspected driver.
- Storage diagnostics report errors, files are disappearing, or the system repeatedly becomes read-only.
- The driver is unsigned, its owner cannot be identified, or malware findings return after cleanup.
- You need to preserve evidence for a work, school, or game-development machine and cannot risk further changes.
At that point, shut the computer down if the disk appears to be failing, preserve the backup, and seek vendor or professional support. Give them the stop code, full file path, signature details, recent changes, DISM/SFC results, and any Defender detection name.
Quick Recap
As an optional shortcut after the manual checks, Outbyte PC Repair can address more than 100 common Windows issues where possible, including broken system elements and shared DLL problems, and includes cleanup, vulnerability checks, a real-time boost, file shredder, and app-crash log features. It runs on Windows 11, 10, 8, and 7; its free trial is category-based for at least two days before a subscription. It complements antivirus software, results vary, and no tool repairs every crash.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
