Outlook Attatchments

One of our customers is having difficulty recieveing atatchments from one particular outlook client. they are both accessing through Microsoft Outlook on XP.
We have gone in and emulated the user and also changed both peoples message format to plain text as opposed to HTML or Rich text. we cannot see anythign at all wrong wth the account, however she is still having difficulty with this. does any one have any ideas they could give me?
would be extrememly grateful