I can’t open my Firefox. I don’t remember well how this problem came on, but apparently I’ve never made any changes to my computer or Firefox itself since the last time I could launch it successfully. I’m using Windows 7 Pro 64 Bits. Now, whenever I open Firefox, there is always an error message saying, “Couldn’t load XPCOM”. I haven’t reinstalled Firefox since I don’t wanna lose my important bookmarks. I hope you can help me resolve this problem.
Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).
You can re-install Firefox by just making a backup of your settings first. Do it via cloud sync (go to settings and click on sync) or backup the folder in your user directory.
Otherwise here is a thread on mozilla.
This message indicates failure to load
xpcom.dll. Check the installation directory (most probably
C:Program Files (x86)Mozilla Firefox) if it is there.