Just to confirm, it's the computer crashing, not Firefox?

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

Perform a System File Check to fix corrupted system files

Win 7, 8, 10, Vista: https://support.microsoft.com/en-us/kb/929833 Win XP: https://answers.microsoft.com/en-us/windows/forum/all/windows-xp-scan-and-fix-disk-errors/6fe2827a-4be6-4bc1-8083-5139b5aa3a3d

Wiki - Windows 10 System File Check http://answers.microsoft.com/en-us/windows/wiki/windows_10-update/system-file-check-sfc-scan-and-repair-system-files/bc609315-da1f-4775-812c-695b60477a93

It is indeed my computer crashing, not Firefox.

1. Tried that now. It does not seem to solve this issue

2. I performed a system File Check and found a corrupted Amd64\CNBJ2530.DPB file and tried following this https://support.microsoft.com/en-us/help/929833/use-the-system-file-checker-tool-to-repair-missing-or-corrupted-system as you suggested (on windows 8.1 btw) but I stumbled on the probleme where I cannot seem to find a known good Amd64\CNBJ2530.DPB file therefore I cannot complete said step. Any suggestions on how to obtain this. I think this might be the source of my problems.

Thanks in advance

Post your question here https://support.microsoft.com

http://answers.microsoft.com/en-US/windows/forum/windows_10

With a link back to this page.

Thanks so much. I think this might do the trick

Keep us posted.