Cannot access user files on HD taken from another computer

Cannot access user files on HD taken from another computer

My son's laptop (running Win XP) died. He took the HD out and put it into an external HD enclosure. It is connected to another computer running Win XP. However, when he tries to get his files from Documents and Settings on the external HD, he gets a 'Folder not accessible' message. I presume this is a permissions issue. Is there any way to get at these files?