Attachments corrupt when sent out of outlook or outlook express 6 on xp.

[GoUNT]

I have recently updated several machines in my office to XP pro. All
are working great but one is having trouble sending attachments. The
attachments seem to send OK but when the receiver gets the email the
attachments won't open. But once in a while it sends fine. I have
tried reloading OE 6, I have switched to Microsoft outlook, I changed
to plain text and still the same problem.

I am whipped I can't even think of what to check next. The network
connection seems to be fine, no problems receiving mail or using the
network file server. I also deactivated the virus scan Norton 2003.

Thanks,

Tony