Cause: Any number of circumstances may cause various unhandled exception errors. The example above happens if NETS loses communication with the Analyzer before users attempt to run a Test Script.
Solution: Open the Windows Task Manager, find the NETS application, right-click on it, and select End Task. Restart NETS and re-run the last attempted test.
Source: NETS User Manual, Revision D, document 132-06035-0006, section 11.2.8.