ERROR MESSAGE WHEN OPENING EXCEL....

Richard J 60 Reputation points
2025-11-19T21:28:40.9+00:00

In the last two days, every time I open an excel file, I receive an error dialog box (see attachment). I click on ok, the box disappears, and I am able to go about my business as usual.

Why does this error appear? Anyone know? Can I stop it? Or just let it freak itself out?

Thank you for any help, suggestions, comments, or advice.

z-Error in Excell

Microsoft 365 and Office | Excel | For home | Windows
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Anonymous
2025-11-19T22:12:33.3966667+00:00

Hello Richard,

The message indicates that guard64.dll in C:\Windows\system32 is either corrupted or not compatible with Windows, and it’s usually linked to third-party security software like Comodo or similar. This often happens after a Windows update or system restore because the DLL no longer matches the current system configuration. You can keep clicking OK and continue working, but the error will keep appearing until it’s fixed.

The best solution is to repair or reinstall the related security program, or uninstall it if you don’t need it. Running System File Checker (sfc /scannow) and DISM (DISM /Online /Cleanup-Image /RestoreHealth) can also help repair system files. If you want a quick fix, removing the problematic software or disabling its add-ins in Excel will stop the error.

This might help

https://support.microsoft.com/en-us/topic/use-the-system-file-checker-tool-to-repair-missing-or-corrupted-system-files-79aa86cb-ca52-166a-92a3-966e85d4094e

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  1. Richard J 60 Reputation points
    2025-11-23T22:34:21.1+00:00

    This worked, thank you so much....!!

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