iTunes 7 Permission Problem

Hi,

Whenever a user opens iTunes 7 they are met with:

There was an error storing you authorization information on this computer.
Try doing a repair install on iTunes from the "Add or Remove Programs" control panel.

and

The iTunes Library file cannot be saved. You do not have enough access privileges for this operation.

This doesn't happen on admin accounts, the users have write/modify access to the local directory "c:\programs files\iTunes\" and the My Music folder where their music library is stored.

What other permissions can I set?

Thanks
-T

HP Windows XP Pro