Something on your PC changed, or upgraded, or updated. Windows Restore back
to a date when it did work may help.
If a basic reinstall did not work, you will need to fully uninstall as
instructed here:
http://usa.autodesk.com/adsk/servlet/ps/item?siteID=123112&id=2887771&linkID=9240617
Restart Windows and reinstall.
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Dean Saadallah
http://LTisACAD.blogspot.com
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