I am about to do the same thing - move my DVICO Dual Tuner across to a new Shuttle SB83G5M (
http://au.shuttle.com/Product/Barebone/SB83G5M.asp) to cut down on the size of the unit.
I don't know what would be causing it, but all I can recommend is to try using the install disc that came with it first, then upgrading the drivers after you have it running?
Regards,
Shane.