...the other account is a "limited" user and as such, the correct permissions need to be given by the admin so the limited user can access the files..

OR...

On the other hand, if the files open just fine from the first users AND if the second user IS an administrator, then you might check out the link below for TAKING OWNERSHIP of those files.

http://support.microsoft.com/kb/308421

Hope this helps.

Grif