Recently when I compute shadows (default of high quality) it causes my computer to freeze up (i.e. no mouse movements or keystrokes have any result)

Sometimes it freezes before the 1st lighting bouce can be done, but I have also had it freeze up when it was on lighting bouce 4. Please fix this problem soon. It is rather annoying having to restart my computer every time I try to compute shadows
Regards,
Zack11