Now, I am experiencing a similar problem. to my post: http://forums.autodesk.com/t5/AutoCAD-2010-2011-2012/Double-Click-Actions-and-Key-Shortcuts-not-work...
I cannot double click to edit. The error message I receive is: "Attempted an unsupported operation." or it opens up properties window.
I cannot copy/paste. The error message I receive is:
Command: _pasteclip Duplicate definition of block _ArchTick ignored.
Duplicate definition of block MSME ELEV SYMBOL ignored.
Current settings:
PICKFIRST - 1
DBLCLKEDIT - ON
ATTDIA - 1
CUI - Double CLick Actions - ON
AcEAttEdit - Unknown because this is 2011 version
AFAIK - Unknown because this is 2011 version
Any help you could offer would be greatly appreciated.