Restoring and resetting the acad.cui file
You would like to undo changes made to your acad.cui file by rolling back to the previous customization state or to the original acad.cui file.
To restore an acad.cui file, in the AutoCAD Customize User Interface right-click on the ACAD element at the top of the tree view, and then click either Restore ACAD.CUI or Reset ACAD.CUI (see graphic below).
The ACAD.BAK.CUI backup file will be used.
Note: The ACAD.BAK.CUI file is created when you make changes to the current acad.cui file in the AutoCAD Customize User Interface.
The original acad.cui file will be taken from the C:\Program Files\AutoCAD 2007\UserDataCache\Support directory.