Avid Xpress Pro 5.7 installed on Mac Pro seems to work well without any issues. Avid has sorted out the reverse playback issue of source clips in source monitor in this version.

In PC we had the issue of hanging. System hangs when the resolution motion is toggled to full green mode or choosing DV source in Capture. Posted on Avid Forums and yet to get clear cut solutions.

So wait till Avid solves the issues with PC and dont hurry up in upgrading to Avid XPress Pro 5.7 for PC.

Note: Avid Xpress Pro 5.7 works perfectly in Intel Mac Pro.