Pro Tools MP Setup and General Troubleshooting
 

I'm also having a similar problem. My 8-core Mac Pro came shipped with 10.4.9 and the combo update will not run. Apple care also confirmed this with me. I have installed Pro Tools 7.3.1cs3 M-Powered and Pro Tools will not launch. In fact I'm lucky if the icon even bounces in the dock. It doesn't crash my computer though. Any help would be greatly appreciated.