Hyperlink changes when mailing

[diane Garrini]

All our sales guys have a d: structured in the same way,
every month they update their excel files from a Cd so
their sales files are always current and every body has
the same ones.

A template file containing hyperlinks to thes files on the
D: is sent to them via email every month. They used to
just save the file and the hyperlink would be the same -
ie pointing to the D: files. Now, the hyperlink refers to
a tempfile when it is mailed to the guys. Why does the
hyperlink change and how can they keep the original
hyperlink?

Thanks