I have tried uninstalling from the control panel as well as manually deleting the install folder from the C drive. I download the latest version of FF to reinstall from a fresh version, but I still get the error and cannot get FF to open or launch at all. I am running a 64 bit system.
Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:
Note: You might want to print these steps or view them in another browser.
Please report back to see if this helped you!
Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.
Download a fresh Firefox copy and save the file to the desktop.
Uninstall your current Firefox version, if possible, to cleanup the Windows registry and settings in security software.
Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.
Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.
Unfortunately, this did not seem to work. I still get the xpcom.dll error. Unless there is more specificity to performing a clean re-install, or I am missing some crucial step in the process, then I am afraid I won't be able to run Firefox.
I am having the same problem. I have uninstalled Firefox and deleted the C:\program files (x86)\mozilla directory before reinstalling.
OS is Windows 7 64 bit.
One more thing this only occurs when Outlook or Word is open, also even when I open Outlook in safe mode so no add ons are running.
I also have this problem with Windows 7 and firefox 23.0.1 I've done a clean install after deleting the firefox directory as recommended. It doesn't happen all the time. I can launch firefox with no error, shut it off, and relaunch immediately (without starting any other programs) and get the error.
Or it can go the other way, launch, have error, shut off, re-launch OK.
The error doesn't seem to be causing any loss of functionality of Firefox.
Start Firefox in Safe Mode to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance).
I updated the Quicktime plugin and the problem seems to have gone away. (Not 100% certain as it was intermittent). Quicktime had been flagged as out of date. This was the only plugin that was out of date.
Update: This wasn't it as the problem is back. Firefox reports it is trying to start nsAppShell and failing.