In Land Desktop 2004, there is a well documented problem where undo just stops working when it encounters an INTELLIZOOM operation and reports that there is "nothing to undo." I've researched this issue thoroughly and, despite the fact that many people have experienced it, it appears that there was never an official word from Autodesk about it.

For what its worth, when I've seen this behavior, the QSAVE command causes several UNDO commands to perform automatically. This appears to have been an equally frequent issue among users with no publicly documented solution.

From my troubleshooting, I've determined this much:

• When starting a fresh drawing, UNDOCTL = 5. After issuing several standard AutoCAD commands, UNDOCTL is still set to 5. Likewise, before issuing any undo commands, UNDOCTL is still set to 5. After undoing a few commands, undo reports "nothing to undo" when undoes an INTELLIZOOM operation. At this point, UNDOCTL = 1.
• It's not tied to the hardware or OS, since other users logging in to the same computer can undo just fine. It has to be tied to the windows profile.
• It's not related to the affected users AutoCAD profile, because I can export her profile to an ARG file, and then import it to another station, where UNDO works just fine.
• It's not caused by any 3rd party software, since the affected user isnt running any add-on apps.
• Running a dummy "check points" does not correct this behavior
• A repair install does not correct this behavior.

For reference:
• http://discussion.autodesk.com/thread.jspa?threadID=369777
• http://management.cadalyst.com/cadman/article/articleDetail.jsp?id=101912
• http://discussion.autodesk.com/thread.jspa?messageID=4584
• http://discussion.autodesk.com/thread.jspa?messageID=5296

Workarounds: No reliable workarounds for 2004

First Appeared: AutoCAD / Land Desktop 2004

Current Status: Undos flakiness has gotten gradually better with each subsequent release. To date, however, nobody has provided a reliable solution when 2004 starts to behave this way.