MOSTLY when I return from the lock screen. I have made it a habit when I leave my computer to always lock my computer, and I can confirm that Firefox does this 100% of the time when returning from the lock screen.
It happens at other times, too, but not nearly as much. I have had it happen without the lock screen a few times only. But locking it is a guaranteed way to trigger the bug, for me, anyway.
Affects me in Karmic, 32 bit.
MOSTLY when I return from the lock screen. I have made it a habit when I leave my computer to always lock my computer, and I can confirm that Firefox does this 100% of the time when returning from the lock screen.
It happens at other times, too, but not nearly as much. I have had it happen without the lock screen a few times only. But locking it is a guaranteed way to trigger the bug, for me, anyway.