The iTunes download feature at www.apple.com doesn't work. It says there's a special error. My original iTunes on my iMac got corrupted somehow. It seemed to become corrupted after I loaded a bunch of my songs into it. Has anyone expereinced this?
that happened when i installed hackintosh on my moms HP (which was temp install anyway and it's back to vista now so i don't know a fix) but i have not had this happen to my macbook but you might try deleting the actual iTunes app in applications then re-downloading and re-installing also maybe try deleting ~/Music/iTunes/iTunes Library (not the music folder itself but your library database files sorry can't help much more