We do not have enough info to think this has anything to do with Firefox. More than likely if you had firefox open and only firefox open than i can assume firefox. Please give us the links that you were on if you can reproduce this without anything else open.
Also firefox-3.0 is not supported any longer and will only receive security updates and urgent bugs. Can you please try using Firefox-3.5 from Ubuntu repos in Jaunty and/or Karmic depending if you have a Karmic partition. I will mark this as firefox-3.5 just to place hold until we get more info ** Package changed: firefox-3.0 (Ubuntu) => firefox-3.5 (Ubuntu) -- computer completely locked up and would not shut down https://bugs.launchpad.net/bugs/485310 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs