phone crashes when asleep.

[Jsaeger98]

3 times since the ICS update, my phone has essentially crashed in the middle of the night. 2 of the 3 times my phone apparently restarted while I was asleep. I woke up to blank frozen white screen. The third time it froze while asleep and I could not unlock the screen. All three times i had to pull the battery in order to restart the phone. Anyone else with this problem?