Error with Clustering in baking

Every time I try to bake my lighting I get the following set of errors:
Error creating external process ‘C:/Program Files/Unity/Editor/Data/Tools/JobProcess.exe’ : The operation completed successfully.
Error cleaning up external process: The handle is invalid.
Failed executing external process for ‘Clustering’ job.

I have no idea what to do with any of these error messages and I’ve been getting them for days. “The operation completed successfully” ? Huh?

I am using 2017.1.1.p3 (updated yesterday to fix a problem where it was constantly crashing.

Just realized this is probably in the wrong subforum. Sorry!