There's something definitely wrong with the CAT 7.3 drivers.
Over three times during
Shivering Isles tonight, I completely lost video. The screen went completely black, there was no recovery other than to hit the Reset button on the front of the case.
After this happened the 3rd time within a couple of hours, I decided to uninstall the NGO CAT 7.3 drivers and revert to the CAT 7.2s. Since doing so, I've had no problems whatsoever.
I hope whatever it is they introduced that brought on these problems is fixed before the 7.4s.