I have been running ST2.5 on a 64 bit Win 7 Professional for a couple of years now in both Sonar and BiaB with no problems. If the forum search doesn’t help you may need to wrap ST2,5 with a program like J-bridge: http://jstuff.wordpress.com/jbridge/

I use J-bridge on 32 bit VST and VSTis when Sonar’s automatic bit-bridge doesn’t. Sonar may have automatically wrapped ST2.5 on my system, don’t know. All I do know is that ST2.5, which I have had for quite a while now, worked from the git-go in BiaB.

Whenever I get something stuck in the back of my throat, I dislodge it by drinking a beer.
It's called the Heineken Maneuver.

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware