I've seen this within the last ~1 week, however I don't have the most recent firefox. If nothing has been proactively done to fix the issue, it's still going to be there!
-- FF flashes up "Not responding" dialogue even when it is https://launchpad.net/bugs/33442 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs