Couldn't load XPCOM.
Couldn't load XPCOM error appears when Mozilla is initiated?
Alla svar (2)
See if this helps. https://support.mozilla.org/en-US/questions/1229392
If you have data you want to keep, you can download a different version of Firefox, sync to get data in new install (in a different directory), and then reinstall this version.
Ändrad
Just a quick follow-up question: is this an MSWin-specific error (i.e. is XPCOM only used on that platform or also on Mac and other Unices)?