I have a iMac that freezes regularly with iTunes 11.0.3. Suggestions?

I find that basically when I launch iTunes on the iMac, select Apps, Check for Updates - while downloading app updates, my iMac freezes with the rotating beach ball. The App in the process of download at the time will freeze (for example just now it was Word Lens frooze at 22 seconds remaining). After waiting for hours, the beach ball is still spinning and I'm forced to perform a Power Off / Power On.

iTunes seems to be the only program that results in this behavior.

Suggestions?