Document full of garbage-what format?

I have a user who has several documents on CD from his former employer. A few of them, with .doc extensions, appear to be junk. They open in Word with just lines and lines of little boxes, with the occasional random letter. WordPerfect doesn’t recognize it at all to convert. Is there any way to determine if the document might be in another format, or if it is just corrupted? They were sent to him, so he has no idea what format they might have been, and doesn’t know where they orginially came from. I’m guessing that if Word (2000 and XP) and WordPerfect (10) can’t convert it, that it’s just corrupt…