When I first upgraded to 64 bit, I had a problem with a few plug-ins as well. Here is something I found that helped.
Initially, I just put all the .dll files in the Steinberg\Cubase\VST plugins folder and almost NONE of them worked. I figured out that the ones that were not compatable was causing some of the others that were compatable not to work. The best explanation I could come up with was that as Cubase scans that folder, if it runs into a problem, it aborts the scan of the rest of the folder or something. What I did was to move them all out and move them back in one at a time. If you find one that screws the process up, take it out.