Some questions/suggestions:
- Very important: did you have any hard- or software changes on your computer recently, which includes drivers, skinning software, plugins, etc.
- Did you try deleting the preference file
- Have you removed any Photoshop leftovers after uninstall (Photoshop directory, my documents directory, program files/common, registry, etc)
- Do you have the same problem with existing documents
- Are you experiencing other weird problems/errors on your computer, especially with other graphics software
- Have you run some hardware diagnostic tests, like memory tests, hard drive tests, cpu test, motherboard test, etc.