There have been reports of the following issue with AutoCAD and Revit. It will not start up and there will be an LMU.exe crash on Windows 7 x64.
The error is: Autodesk Component has stopped working.
When you show the details, it will mention Pen_Tablet.dll and this would indicate that you have a Wacom tablet. If you uninstall the Wacom Tablet software, AutoCAD or Revit will run as expected.
David Lau