Computer crashing under heavy graphics use, only when LR & PS installed on system.

I have been having an issue I believe related to the most recent PS CC '14 and LR 5.5 release through Creative Cloud. My video driver will crash, with any application that makes heavy use of my graphics card. When I uninstall PS & LR, the problem goes away, and returns after reinstall and use. Computer is running Windows 7 w/ Nvidia GT640. Problem didn't exist prior to the most recent updates. Nvidia drivers were purged and reinstalled.