Yes, migration is the problem: you had a problem in 2010, and by migrating,
you took it along with you to 2011.
Backup all of your files, and all of your customizations for both programs.
Follow Autodesk's Uninstall AutoCAD instructions:
http://usa.autodesk.com/adsk/servlet/ps/item?siteID=123112&id=10243968&linkID=9240617
--
Dean Saadallah
http://LTisACAD.blogspot.com
--