I have the same problem. Tried 3.3.0. which loaded and upgraded Virus OS. When I tried to start in Cubase 5.1 I got the message that driver did not fit. Uninstalled again. I have tried to install with different USB connections without result. Tried earlier on an XP machine with good results, but in Windows 7 it just does not work.
Can´t find any dll's to take away. Anyone who knows where to search?