I did a deep cleaning of Firefox, removed all downloads, and used CCCleaner. So for now it seems like it works well.

https://support.mozilla.org/en-US/questions/1425129

Try restarting in troubleshoot mode. You could also check for malware.

https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems https://support.mozilla.org/en-US/kb/troubleshoot-issues-related-to-add-ons

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

This might be a problem with the Windows MRU list that contains references to (removable) drives that no longer are available.

Try to delete the MRU (Most Recently Used) ComDlg32 registry keys with the registry editor (regedit.exe).

• https://www.google.com/search?q=clear+mru+windows+11&num=100&newwindow=1

Try restarting in troubleshoot mode. You could also check for malware. https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems https://support.mozilla.org/en-US/kb/troubleshoot-issues-related-to-add-ons

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https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

For those who can face this problem: it was fixed after running adware cleaner. For the note: I have working and fully functioning antivirus, but adware cleaner found some file "C:\Users\User\AppData\Roaming\Mozilla\Firefox\Profiles\g7lmrb96.default\invalidprefs.js" that was deleted and after reboot problem was gone. I've read that file and didn't find any malware or adware but anyway - problem was fixed. Besides this file was created back in 2016 and it seems like containing my own preferences at that period. Why it was persisting for 7 years and not bringing any problems until now? I don't know. File seems to contain just preferences for FF browser.

Terry said

Try restarting in troubleshoot mode. You could also check for malware. https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems https://support.mozilla.org/en-US/kb/troubleshoot-issues-related-to-add-ons

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https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

For those who can face this problem: it was fixed after running adware cleaner. For the note: I have working and fully functioning antivirus, but adware cleaner found some file "C:\Users\User\AppData\Roaming\Mozilla\Firefox\Profiles\g7lmrb96.default\invalidprefs.js" that was deleted and after reboot problem was gone. I've read that file and didn't find any malware or adware but anyway - problem was fixed. Besides this file was created back in 2016 and it seems like containing my own preferences at that period. Why it was persisting for 7 years and not bringing any problems until now? I don't know. File seems to contain just preferences for FF browser.

Some corrections. This file wasn't the cause. During that clean I've removed a couple of files besides invalidprefs.js. Those files: C:\Windows\System32\drivers\{1EC00332-9DA9-436D-9AAA-048787DF45B7}.SYS C:\Windows\System32\drivers\{E7224BCD-D889-4528-8456-60CE0724367E}.SYS

As far as I know these files were created by AceStream media player.

The problem came back and after deleting these files once more, problem gone again so I assume it was the reason truly.

madd.korben said

Terry said

Try restarting in troubleshoot mode. You could also check for malware. https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems https://support.mozilla.org/en-US/kb/troubleshoot-issues-related-to-add-ons

---

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

For those who can face this problem: it was fixed after running adware cleaner. For the note: I have working and fully functioning antivirus, but adware cleaner found some file "C:\Users\User\AppData\Roaming\Mozilla\Firefox\Profiles\g7lmrb96.default\invalidprefs.js" that was deleted and after reboot problem was gone. I've read that file and didn't find any malware or adware but anyway - problem was fixed. Besides this file was created back in 2016 and it seems like containing my own preferences at that period. Why it was persisting for 7 years and not bringing any problems until now? I don't know. File seems to contain just preferences for FF browser.

Some corrections. This file wasn't the cause. During that clean I've removed a couple of files besides invalidprefs.js. Those files: C:\Windows\System32\drivers\{1EC00332-9DA9-436D-9AAA-048787DF45B7}.SYS C:\Windows\System32\drivers\{E7224BCD-D889-4528-8456-60CE0724367E}.SYS

As far as I know these files were created by AceStream media player.

The problem came back and after deleting these files once more, problem gone again so I assume it was the reason truly.

New corrections. My problem doesn't depend neigher on these files: C:\Windows\System32\drivers\{1EC00332-9DA9-436D-9AAA-048787DF45B7}.SYS C:\Windows\System32\drivers\{E7224BCD-D889-4528-8456-60CE0724367E}.SYS

nor invalidprefs.js. After some time problem occurs again.

No solution found.

Open a second window, visit about:third-party and use that to monitor what modules are being loaded when opening a file (Ctrl+O) in the first window.

Open a second window, visit about:third-party and use that to monitor what modules are being loaded when opening a file (Ctrl+O) in the first window.

Thank you for your reply. I've did what you asked for and that is what I saw: browser hangs the same way as before when I press CTRL+O so all I could do is to copy modules that were open before I press it. And here they are (without events class cuz it's long to paste):

     "name": "IPSEng64.dll",
     "fileVersion": "17.2.12.33",
     "typeFlags": 1,
     "signedBy": "Symantec Corporation",
     "applicationName": "Norton 360",

     "name": "nvwgf2umx.dll",
     "fileVersion": "31.0.15.4584",
     "typeFlags": 1,
     "signedBy": "NVIDIA Corporation"

     "name": "nvgpucomp64.dll",
     "fileVersion": "31.0.15.4584",
     "typeFlags": 1,
     "signedBy": "NVIDIA Corporation"

     "name": "nvldumdx.dll",
     "fileVersion": "31.0.15.4584",
     "typeFlags": 1,
     "signedBy": "NVIDIA Corporation"

Open a second window, visit about:third-party and use that to monitor what modules are being loaded when opening a file (Ctrl+O) in the first window.

I've tried to block all of these 4 modules - no effect. Still hanging when press CTRL+O.

You can use Process Explorer or Process Monitor to see what modules are being loaded when opening the file selection dialog.

https://learn.microsoft.com/en-us/sysinternals/downloads/process-utilities

You can use Process Explorer or Process Monitor to see what modules are being loaded when opening the file selection dialog. https://learn.microsoft.com/en-us/sysinternals/downloads/process-utilities

There are a lot of events every second. How can I find the one that causing the browser to halt?

You can create a new profile as a quick test to see if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works, you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

You can create a new profile as a quick test to see if your current profile is causing the problem. See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works, you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

I've tried it already. Profile doesn't matter as well as installed extensions.

Did you check the MRU (most recently used) keys in the Windows Registry like I suggested above ?

Did you check the MRU (most recently used) keys in the Windows Registry like I suggested above ?

There are multiple MRU meanings. First - recently used removable devices that located at branch: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USBSTOR

Second - recent Files and Folders: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\TypedPaths

Third - recently used files in File Explorer: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WordWheelQuery

Which one you meant?

I think I've found the cause: it's on-screen Windows keyboard! I've noticed that after starting on screen keyboard, Firefox hangs the same way. Next, if OSK started, every CTRL+O causes Firefox to hang.

Now: how are they connected to each other and how to fix it? Any ideas?

I think I've found the cause: it's on-screen Windows keyboard! I've noticed that after starting on screen keyboard, Firefox hangs the same way. Next, if OSK started, every CTRL+O causes Firefox to hang. Now: how are they connected to each other and how to fix it? Any ideas?

For the record: accessibility.force_disabled is set to 1, no affect.

Did anyone find an actual solution for this conflict between Firefox and the on screen keyboard?