Did you disable the antivirus when you performed the repair and re-install?
If not, try doing them again with the anti virus turned off.
If that fails, try doing a windows restore and go back to a week before your problems began. I could be an badly behaved update from microsoft that is causing the problem.
Brad - I was optimistic about trying a repair/reinstall with antivirus disabled since Avast did have two hangups the first time...unfortunately neither repair nor reinstall seemed to work, even with antivirus disabled. I have not tried a system restore yet. It's very possible that there was an update over the weekend. Typically I disable auto MS updates but this copy of AutoCAD is on my office PC. The restore may be done today or tomorrow - I will be leaving the office shortly but will let everyone know what happens. Thank you for the help.
Unfortunately system restore is failing and has failed after I tried to restore to five different dates. I think I'm going to have to move to another computer to be able to get work done, so this issue will probably remained unresolved for me. Thanks for the help regardless, guys.
The failed system restore is still troubling (it failed even in safe mode) but others were able to sign onto my computer via our company server and on their own user accounts run AutoCAD successfully. IT completely removed my account from the server and created a new profile for me and suddenly everything is working fine. I don't know near enough about what IT actually went through in doing this, but as far as I can tell everything is working for me now (though I do need to set up a new profile in acad, since I didn't trust any of the old files to transfer problem-free).
Thanks for the help...I'm glad I can go back to doing some work now, though I am sorry that anyone who uses google to find this page probably won't be served by the solution I used.