A new cs update for 7.3.1 is here. At a glance it looks to do for 7.3.1 what the latest cs did for 7.4.

Pro Tools HD 7.3.1cs6 for Mac OS X and Windows XP both include the following fixes:

Fixed: On D-Control and D-Command, the Touch Command Would Sometimes Not Engage When Quickly Grabbing a Fader (Item #87718)
The fader would “push back” and no automation would be written

Fixed: Pro Tools quits unexpectedly when moving a plug-in window while closing it from a control surface (Item #99442)
If a plug-in window was closed from a control surface while the plug-in window was being dragged across the screen, Pro Tools would quit unexpectedly.

Fixed: Opening a Session with an RTAS Version of Dynamics III Could Result in a Burst of Noise (Item #99562)
This problem was intermittent, and would not occur when using TDM versions of Dynamics III

Fixed: Surround Pan Automation is not Updating Properly in Loop Playback (Item # 85802)
The pan positions are correct on the first play of the selection, but can be incorrect on subsequent plays
Please note that there is still an outstanding issue where Surround Pan automation may stick on a particular output. Digidesign is currently working on a solution.

Pro Tools LE and M-Powered 7.3.1cs6 for Mac OS X and Windows XP all include the following fixes:

Fixed: Pro Tools quits unexpectedly when moving a plug-in window while closing it from a control surface (Item #99442)
If a plug-in window was closed from a control surface while the plug-in window was being dragged across the screen, Pro Tools would quit unexpectedly.

Fixed: Opening a Session with an RTAS Version of Dynamics III Could Result in a Burst of Noise (Item #99562)
This problem was intermittent

Digidesign CS updates page