I have been having freezing problems with the new 2011 iMac. I have the 27-inch 3.4GHz i7 model, and it is on almost all day, constantly being used. It seems to freeze at least once per day, while doing normal use, or while gaming or encoding video. When it freezes it makes a clicking sound, and requires me to push the power button until it turns off, then I turn it back on. Anyone else having this problem with their iMac's? Should I restart the computer more often to keep it fresh?