Comment 4 for bug 665796

It happens without any apparent cause to me too, even with the system is idle.

It just appears that under normal operation, it happens 2-4 times a day (completely random, no fixed interval between events); but if I start playing Portal, for example, it happens in less than 30 mins (again, at random, no defined interval).

Switching terminals also takes 10-15 seconds for me, and htop from the console also shows the same unresponsiveness. Shaking the mouse vigorously or flood-pinging from another machine alleviates the problem until it goes away (it makes sense: they produce interrupts that wake the process scheduler; this also explains the high system CPU usage: the scheduler never awakes for normal ticks since there is no timer, but it awakes to process hardware interrupts).