Just thought I'd post this, in case anyone else has the same problem. I had allowed scripts on a specific site before, so after restarting Firefox for the update to 1 of my extensions [coincidentally (or not) NoScript], I decided to give the site permanent permission to run scripts.
At which point Firefox crashed. When I restarted, because I'd given it permission already, as soon as the page started to load it killed Firefox again. I was able to fix this by manually removing permission, by editing the prefs.js file. If anyone should find themselves needing to do this, just open the file in a text editor & do a search for part of the domain name in question. You'll probably find several mentions of it, all under the
Code:
user_pref("capability.policy.maonoscript.sites",
section. Delete all mentions of the offending domain name & you should be able to restart Firefox again without problems.