Outlook Attachment is blank unless opened from forward

Hi All

I Have a strange problem on one of my users PC

he recived a mail from an internal user but when he open the attachment its a blank word doc

but as a work around when he click forward then open the attach from the forward windows the attach is ok

* another user recieved the same E-mail with no problem

* other E-mails are ok

* windows xp Office 2007 SP2

* i used the office diagnostic tool and every thing is ok

* i cleard all the temp files and it did not work

* i created him another mail profile and it did not work

Sorry I know how strange this problem is and thanks for your replies in advance