I would not see why it couldn't, I am running GTP4, and Sonar 8.5 PEx64, all on same laptop(HP). There was a discussion about Guitar Rig on the Sonar forum, I think you have to run it in stand-alone first, and then Native puts their dlls separate from Cake plugs. Is it the guitar rig VST folder, or the GTP3 not showing up? Might just have to point plugin manager to Natives folder, where the dll is. If other way around, not sure, reinstall, and see if it will show up. Good luck!