I've hit this page a few times in a Google search and just now figured out what is going on.
I have a MacBook Pro that I use at home and at work with an external ViewSonic display. At work, the iTunes Artwork screensaver works great on both displays. At home, however, it displays a random amount of artwork on both displays and then hangs until it eventually crashes and shows the computer name screen saver instead.
After checking out a few tests... I too find the screen saver works fine at home if I check main display only. This pointed me towards my external display. What could be different? Oh yeah, my display at home has a slightly higher native resolution (1600x1200 at home, 1280x1024 at work) because its a bigger display.
So on that hunch, I reduced the resolution of my vp201s to 1280x1024--and the screen saver worked fine on both displays!
Hopefully Apple hits this bug in their next batch of updates. At least I feel better figuring out the real problem. Meanwhile this might help someone out there from spinning their wheels trying to solve the problem with the useless recommendations about deleting the settings plist and the annoying quantity of users complaining about the pink color problem (which sounds like it was fixed in 10.5.2--I never saw it) when you try searching for the solution to this problem.
