UPDATE: The version 270.73 driver is available now.
Nvidia and Adobe are aware of a problem with the 270.61 and 270.71 drivers for Nvidia graphics cards for Premiere Pro CS5 and Premiere Pro CS5.5.
A driver with a fix for this issue (270.73) should be available soon.
If you are experiencing problems with Premiere Pro, and you are using the 270.61 or 270.71 Nvidia drivers, please check the Nvidia driver download site for the new driver. You may also choose to roll back to a previous driver until the new driver is available.
We’ll update this post as soon as we learn of the public availability of the new driver.