The question being : is that really caused by firefox, or does the bug happen while you're using firefox, if you see the difference.
Have you used your computer a log without firefox ?
If that's linked to FF, an unprobable though possible possibility : temporarily use another profile (firefox -ProfileManager, create a new one and make it default), then uninstall firefox and reinstall it again in a clean install, see if the bug is back. If it's back, I can't help