Does anyone know why a tempo report would give me a server error when i hot link to it?

It seems there is some issue at the place where you are configuring the link.
Can you check your application server logs for the detailed error.
Also, can you paste your code here you are using so that the other forum members can have a look over it and see if there is some issue.

Avinash- did you ever find out what the issues was? We're looking into hot-linking to tempo reports as well.

This started working automatically with no manual intervention on our part.