You mention MS Outlook in your subject line, so if she is indeed using MS Outlook (version 2000?), I think the Office SP2 is a security patch that disables use of attachments. I’m fuzzy on the patch numbers, so it may be SP3 or higher.
If she is using Outlook Express, she may have her antivirus software configured to delete attachments upon receiving them.
Also for Outlook Express look under “tools” then “options” then “security” and look for a check box about not allowing unsafe attachments or .exe files - uncheck it.