For the last fortnight or so, firefox kept freezing, but it would always fix itself within a minute or so. I did a computer scan and everything was clean and I reduced the number of tabs I had open to try and speed things up, but even when I had only one tab open, it would freeze. Today, it froze and hasnt fixed itself even after 5 hours, and after ive restarted my laptop. A message keeps popping up about 'a script has stopped working' and whatever I press makes no change (stop script, or continue). Im trying to uninstall and reinstall firefox, but I can't uninstall it until the programme is closed. But I cant close it as it is completely frozen. How can I fix this?

Thanks in advcance.