Hyperlink path keeps changing on me

I have a ppt file that only has two hyperlinks in it. When I create the link
it is:

S:\Shared\Presentations\Sign up\Giving Tree\Sign up.xls

After I OK the hyperlink dialog and then Edit the hyperlink again, it
appears as this:

\\tamlrpcapp2\volume1$\Shared\Presentations\Sign up\Giving Tree\Sign up.xls

At this point it still works. I then save the ppt as a pps. It still works
but if I email it to someone, or close and reopen the ppt file it stops
working. Then when I Edit the hyperlink again it has changed to this:

.../../../../Presentations/Sign%20up/Giving%20Tree/Giving%20Tree

Any ideas? I know there are a lot of issues with hyperlinks. I can't believe
MS has such a problem with something that should be pretty straight forward.
It's a good thing the rest of their file management components don't work
this way. BTW, I'm using PPT 2003.