There are many times you want to use a USB hard drive to move files between, for exmaple, Vista, XP, Unix, and MacOS. A drive is formatted with FAT32. Files are added and removed under MacOS and XP and Unix. When viewing the drive on Vista, some of the permissions are very messed up. It cannot access some files or directories. It says some are "shared" and thus can't be deleted, while others are unreadable because they are owned by different users. Everything looks fine on the other OSs.
What is the easiest way under Vista to say "look, just make everything on this drive readable and deletable, OK?". This is a Vista system with just one user.
What errors are you getting specifically and what do the permissions look like exactly?
From http://technet.microsoft.com/en-us/library/cc783530(WS.10).aspx
"On a FAT or FAT32 volume, you can set permissions for shared folders but not for files and folders within a shared folder. Moreover, share permissions on a FAT or FAT32 volume restrict network access only, not access by users working directly on the computer."
Are you sure your user has not made a network share out of anything on that drive? Running net share in a command prompt will display all shared folders.