Thanks mrtomcat!
I've had exactly the same problem with Cubase 5/32bit (under Windows 7/64 Bit), and your posts did help a lot.

Short additional information for other users facing the problem:
Just downloading and copying the Alpahatrack 64 Bit DLL to my Cubase/32 Bit component directory did not yet solve the problem. I had to INSTALL the AlphaTrack 1.3.0 driver to my Cubase/64 Bit directory. Then the copy of the latest Alphatrack/64 Bit  DLL to the Cubase/32 Bit directory worked!
I assume:
1. there must be registry entries for the 64 Bit version of Alphatrack, which are only provided by installing the software for the 64 Bit Host.
2. mrtomcat had already installed the 64 Bit version, so copying the DLL was sufficient in his situation.

thanks again mrtomcat,
Stefan