I've seen the same error message on my Mac when the batch file tries to start the ImageIntegration process, some times it works and completes the process.
When I get an MIME error I just open the ImageIntegration process and load the c_d_r.fit files manually and complete the process.
Cleon
PS after II note the Low rejection % numbers second from the right in the Process Console for RGB or L, if I see any subs with larger then the average Low rejection % I'll open them and see if the tracking was bad and X them, also take a good look at your ImageIntegration Ref sub, the first sub, make sure it's one of the better in the list