You may need to be logged in as Administrator to access the files.
Has this computer got FAT or NTFS configured?
Personally I would use NTFS on all machines.
Have you tried Managing the computer from another to gain access?
Has any security settings been setup on this particular computer. You may need to look in all security policies from Domain right down to the OU's.
Have a look in "Computer Managment" to see if it shows up there.