Outlook sending empty/blank attachments

[Ty]

I have an issue where an end-user is sending an e-mail
with an attachment (word documents mainly)where sometimes
the attachment shows up blank. The attachment is sent and
received but when opening the attachment it is empty. The
attachment is also empty when viewing the e-mail and
attachment in the sent items (of the sender.)

(Hope this makes sense)

Can anyone please help ?
(I am using Outlook 2002 with SP2)