Hi S,
Maybe to do with having the Surround mixer plug in the plug ins folder?? Installs have traditionally defaulted to the Surround mixer (maybe with the Stereo as well, can't remember). I always switch them all out and have JUST the Stereo Dithered plug in there.
I'm interested in show stoppers like this (if it is a show stopper), as I've had a copy of PT9 waiting here since before Christmas, but haven't had a suitable break in proceedings to give my machines a full birthday and try PT9.
Let me know if that helps mate.
Cheers
Steve Bush
http://music180.com/pros/5887