Help, I can't think of anything else to do!

I recently bought an old Navis-Pro card that uses the Conexant (?) chip like the Hauppage PVR-250 and others. I have it working fine on MPEG-1, SVCD, and VCD captures. However, if I try to use MPEG-2, I get the following error:

"An error occured when connecting to downstream filters. System restart or reinstall Navis-Pro program. (Error Code 1121)"

I have Direct X 9 installed, and about every codec that's in use. I run Pinnacle Studio 9 without a problem, ditto Media Player Classic. And yes, I have de and re installed the program many times with registry cleanings inbetween. Pentamedia, the manufacturer is of no help. I've searched this site and Googled the net to no avail.

I'm out of ideas. Do you have any?

thanks, pzo