The newer Nvidia drivers are to accommodate the GTX 400 and 500 series Fermi cards. Drivers 260.89 and 266.58 create BSOD problems (Photoshop, AutoCad) for my GTX-275 card. What works well for me is the previous old driver 258.96
This is a case when newer is not always better!
Win 7 updates also help. I wanted to wait until June for the bugs to be worked out, but jumped the gun and went ahead and installed SP1. No problems experienced so far (3 weeks).