I've had a similar problem with itunes as well. Here's what I did, and so far, so good. What you want to do is clear the PRAM. Shut down yoru computer. While holding down the apple key, options key, P, and R, thru the power on. Keep those 4 keys down until the computer restarts twice. (until you hear the THIRD "chime") This clears yoru PRAM, and should solve the problem. When you log back in, you'll have to set the date and time again.