So after I updated to 10.7.2 my iMac is doing some weird stuff. It happend to me twice now. I was just watching a podcast in iTunes and suddenly it freezes, the screen gets a bit darker and it's telling me ( in several languages ) that I need to restart my computer by holding down the power button. I can't dismiss this message or anything! Once my machine is back up , it allows me to report something to apple because my system shut down because of an ' error ' . Any ideas?