Windows 11 notification system and Settings app crashing with memory access violations

I have been having an issue very much the same thing and after 24 hours, I have had 0 issues with a specific change.

TL;DR — Root cause: HVCI (Memory Integrity) on Windows 11 25H2 build 26200 is falsely enforcing Control Flow Guard violations across system-wide processes. This is an OS-level regression in Microsoft's hypervisor-based code integrity enforcement. Disabling Memory Integrity immediately resolved all crashes. I am only 24 hours in, but with no issues, that track record is breaking records for me.

Details:

I have actually been digging into this in depth with Claude and I think it has found the likely culprit after many days and many hours troubleshooting my problems. No, this is not chkdsk, sfc, dism related. I ran each of those at least a dozen times. This first started with Brave browser crashing every day with the same error, STATUS_ACCESS_VIOLATION. Well, after digging, I found out it wasn't just Brave.

Over 105 days, I logged 82 crashes across 21 different applications, all with the same two exception codes (0xc0000005 and 0xc0000409). The most affected were Windows Defender (MsMpEng.exe / mpengine.dll) with 25 crashes, Brave Browser (chrome.dll) with 19 crashes, Windows Update (MoUsoCoreWorker.exe) with 8 crashes, and PowerShell (clrjit.dll) with 4 crashes. Other affected apps included Task Manager, Chrome, SearchIndexer, Explorer, svchost, NVDisplay, SecurityHealthService, GameBar, sppsvc, and more.

Brave and Chrome displayed the error in-browser as "Aw, Snap! Error code: STATUS_ACCESS_VIOLATION".

What I Ruled Out

• Bad RAM — MemTest86, 4 full passes, 0 errors (64 GB DDR5)
• Corrupt system files — sfc /scannow + DISM /RestoreHealth, all clean
• Browser extensions — disabled all, crashes continued in 20+ other apps
• GPU driver — updated NVIDIA RTX 4070 Ti driver + disabled hardware acceleration, crashes continued
• Dual antivirus conflict — fully uninstalled Malwarebytes, crashes continued
• BIOS/ME firmware — updated both, crashes continued
• Corrupt Defender definitions — MpCmdRun.exe -RemoveDefinitions -All + re-downloaded, crashes continued
• Browser profile corruption — both Brave and Chrome crashed with same errors

The Fix

Settings > Privacy & Security > Windows Security > Device Security > Core Isolation > Memory Integrity — turn it OFF, then reboot.

Result: Zero crashes since disabling HVCI. The system went from ~0.8 crashes/day for 3.5 months to zero crashes immediately.

Why This Is the Cause

0xc0000409 is the Control Flow Guard (CFG) fast-fail exception code. HVCI enforces CFG at the hypervisor level. When HVCI falsely flags legitimate code, it terminates the process with this exact exception. 0xc0000005 (access violation) is the downstream effect of HVCI's stricter memory protection enforcement in 25H2.

The crashes affected 21 completely unrelated applications that share no common library or framework — the only thing they share is running under HVCI on build 26200. Disabling HVCI was the only change that resolved the issue, after systematically ruling out every other cause over weeks of testing.

System Details

OS: Windows 11 Pro 25H2 Build 26200.8037, Intel 14th gen CPU, NVIDIA GeForce RTX 4070 Ti (driver 32.0.15.9579), 64 GB DDR5, Defender Platform 4.18.26020.6 / Engine 1.1.26020.3

This appears to be a regression in HVCI enforcement in 25H2. The PC reset that resolved your issue likely worked because it reset the Core Isolation / Memory Integrity setting to its default state. I'd recommend checking whether HVCI was re-enabled after your reset.

Hello ephemeral8997,

The most effective next steps are, Re-register the affected system apps (Settings and ShellExperienceHost) using PowerShell to refresh their manifests. Verify the DLL versions against your OS build and replace them from the latest ISO if they’re mismatched.

Check for third-party shell tweaks like StartAllBack or ExplorerPatcher that often hook into Action Center and cause crashes remove them temporarily and finally, if all else fails, perform an in-place upgrade with the latest Windows 11 ISO to repair components without wiping your data.

This might help

https://thegeekpage.com/systemsettings-exe-crash-when-using-windows-11-fix/

Standard Disclaimer: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.

Obviously, I have tried the generic things like sfc / dism and resetting the notification panel, resetting components, whatever. Not even sure what caused that problem anyway.

It appears that you are experiencing crashes related to the notification settings in Windows 11 Pro version 25H2. The exception codes you provided (0xc0000005 for SystemSettings.exe and 0xc0000409 for ShellExperienceHost.exe) indicate memory access violations, which can occur due to various reasons including corrupted system files, issues with the installed updates, or conflicts with other software.

Here are some steps you can try to resolve the issue:

1. Run System File Checker (SFC): This tool can help repair corrupted system files that may be causing the crashes. Open Command Prompt as an administrator and run the command:

sfc /scannow

Wait for the process to complete and then restart your computer.

2. Check for Windows Updates: Ensure that your system is up to date. Sometimes, Microsoft releases patches that resolve known issues. Go to Settings > Update & Security > Windows Update and check for updates.
3. Reset the Settings App: You can reset the Settings app to its default state. Go to Settings > Apps > Apps & features, find the Settings app, click on it, and select "Advanced options". Then, click on "Reset".
4. Create a New User Account: Sometimes, user profile corruption can cause issues. Try creating a new user account and see if the problem persists when logged into that account.
5. Perform a Repair Install: If none of the above solutions work, you might consider performing a repair install of Windows 11. This can fix system issues without affecting your files.

If the problem continues after trying these steps, you may want to report the issue through the Feedback Hub or seek further assistance from Microsoft Support.

References:

• Windows 11, version 25H2 known issues and notifications