Jason Thomas submitted the following solution, and asked me to share it with the Autodesk community:
Jason installed AutoCAD 2012 on a Windows 7 64-bit system with an ATI Radeon HD 5800 graphics card and Catalyst 11.5 drivers. He found the image to be completely unreadable for text and significantly blurry for lines, except for the area under the crosshairs. Anywhere he moved the crosshairs, the image cleared up, but only stayed clear where the crosshairs were.
In the Gaming section of the Catalyst Control Center application, under 3D application settings, Jason unchecked the box for Morphological filtering under Smoothvision HD: Anti-aliasing. This fixed the blurriness issue.
Thank you for sharing your solution, Jason!