In this document bellow you can find the latest drivers for supported tape drives and robotic libraries and also a list of supported devices:
http://seer.support.veritas.com/docs/251466.htm
I was getting the same thing, where my backup exec would sit in Loading Media, but after I updated my backup exec with the latest drivers, also I got the latest drivers for windows 2003, it worked.
So try it out and let us know if you still have problems.