Im getting similar problems. I think it has something to do with WMP on vista, whichever version it would be. It seems like when the Soundtap driver is enabled, if I try to listen to anything in WMP it wont work, and when I go to exit it, it will blue screen me. It was even so severe the first time I did it, when I rebooted, it said that my copy of Vista was not registered and I had to go through and RE validate the OS. Definitely not what I was getting into.
Also, I tried, but only briefly for fear of system crash again, to record something from iTunes, and it did not seem to work.