I have Pro Tools LE v8 on a Mac Desktop with Leopard and 4GB RAM. This is totally stable and I can run many instances of RTAS plug ins. However, Garritan is proving the exception. It frequently flags up the CPU warning in Pro Tools and the only way it runs stable is on a single track in a new Pro Tools project. Add a couple of tracks or another instance of GPO and the warning comes on after a few seconds with very distorted audio. Buffer size to maximum improves the problem but does not cure it. I have turned off ambience and reverb etc, but GPO still proves almost impossible to use. This is a real puzzle.