Reply #1: Do you use extensions?

[charlie]

If so, try running in Safe Mode. Quit Firefox. Click Start, and in the search box enter

firefox -safe-mode

and press Return. Tick the "Disable all addons" box in the dialog that pops up and click the "Continue in safe mode" button.

https://support.mozilla.com/en-US/kb/Safe+Mode

If that fixes the crashes, an extension is almost certainly the culprit. Restart in normal mode and disable all extensions, save one. Close and restart again. If it crashes, you've found an extension that causes it. Disable it. Enable the remaining extensions one by one, with restarts in between, to test the rest of them.