Outlook Express all messages not showing

I have a client who uses Outlook Express 6, he was using the system when all of a sudden OE close with a fatal exception error.
Now, whe he goes back to the in box there are only 3 messages where once was around 600. The size of the inbox is still 545Mb, so the messages are still there but can not see them. Have tried importing to MS Outlook and Netscape mail but all it imports is the 3 that are already there.
Any suggestions would be apreciated.