well this can happen on a machine with no plugins and just left sitting at the gmail page.... gets worse with visits to youtube and such. Now I have 3 PCs, two with XP one with Windows 7, it happens on one XP and the Windows 7 box, one XP machine is just fine. And yes I do run add-ons and such, the same on each machine, but ive tested on clean re-installs and it does it. A bit of googling you find other with the same problem.... its not everyone out there.....but its still not enough to drive me away from Firefox, its not much of a pain to restart every few hours.