ndr attachment not visible in outl. 2000

When in exchange 2000, i send a non delivery report to a certain user that uses outlook 2000, he can see that the original mail is attached to it, but there is no way of opening it.
When i configure outlook express on the same machine, using imap, you can view the attachment.

This confirms that the attachment is really there, it looks like ol2000 misinterprets it somehow.

I have this problem at two different customers now, so an answer would be very welcome.

Thanks