Though it is quite unlikely that RevitLookup has anything to do with a Dynamo script, you can navigate to the path where the file "RevitLookup.addin" locates and temporarily move it to someplace else in order to make Revit not loading it at startup, ruling out RevitLookup as the cause of the exception at least.
Svetlana Dragomir, Plugin Designer
Partner, Senior Software Developer, Traveler