iTunes on Lion taking over my MBP (90% CPU, 3+ gig ram)

I'm having troubles with iTunes taking over my computer. If I leave iTunes running and walk away from my computer for more than a few hours, when I come back my computer is unusable. The mouse responds, but that's usually it. The keyboard either doesn't do anything or is hugely delayed. I can't switch windows or interact. I almost always have to reboot.

I've left activity monitor running 4 times now and it's always iTunes taking it over. Today, the CPU for iTunes was at 90% CPU and its was using about 3 gigs or ram (I have 8 total).

Any ideas on how to fix or debug iTunes?

Thanks

phil