Some of my itunes purchases are showing that 'this track is not available to this computer' despite this being the PC they were bought on, and only computer they've been played on.

Couldnt find any help on the itunes site. Am I right in that is an authorisation error (AKA Apples DRM), or something else?

OK, *think* i've fixed.

Some reason Vista has set up some sort of sync, and the files hadnt been sync'd correctly so show as 'offline'. I've removed, and everything appears OK again.

Which is filling me with fear about a network drive to store music etc on!!!