Updated yesterday. Keeps crashing since I restarted machine this morning. Sending numerous reports. Can I install another copy over the top of this one or should I uninstall it first? Afraid of loosing all my addons.
Remove the current installation, but do not delete "personalizations" when offered. Then do a clean install.
Doing that, your bookmarks, cookies, and extensions will be preserved.
If that still does not work, then start Firefox in "Safe mode" using that Firefox option in the Start menu. If Safe mode works, then the problem is with one of your add-ons: Remove them all, and re-install them one at a time, checking for problems.