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-Information FAQ http://forums.adobe.com/message/4200840
Also, what you describe is USUALLY caused by an automatic Windows update (are you Windows?) that "breaks" something in the graphics display driver as it relates to PPro
So... what is your graphics adapter, and have you gone to the vendor site (NOT Windows Update!!!) to check for a newer device driver
IF you have an nVidia card, How to determine your nVidia driver version
Right click in any open area of the Windows desktop
Select NVIDIA Control Panel from the popup window
Select SYSTEM INFORMATION at the lower left corner
Driver version should be the 1st line in Details
I have a GTX285 using driver 296.10