We're seeing an issue with AutoCAD 2009 freezing on launch. This occurs with working drawings and blank docs. It's happened on several computers. In one situation, rebooting the PC solves the problem for a day or so. In another situation, uninstall/reinstall did not work and we had to restore from Ghost.
We're running AutoCAD 2009 on Windows 7/64-bit. This is an officially unsupported config. We've been running this way for nearly eight months on 12 systems. It's a little quirky but overall it works just fine.
This issue has cropped up recently.