I have a Dell pc dimension C 521, windows XP SP2 and am suddenly have lots of problems with Mozilla Firefox freezing on me. I keep shutting down and rebooting, I have tried uninstalling and reinstalling version 3.63. I have also tried system restore Often it doesn't load properly I just get the minimised box and cannot get it to full size.I am at my wit's end. Have you any suggestions. Please in plain English and I do not understand computer jargon too well.I have avast antivirus and zone alarm firewall free versions of both.