What does "MIDI" mean in the EDP IV display?

["Neil Goldstein" <ngold@attbi.com>]

I assume it means Midi overload. Couldn't find it in the manual. 

The EDP shows it is receiving clock, and I'm not recording, but after 20
to 30 seconds the display shows "MIDI", functions are locked up, and I
have to go into Parameter edits to clear.

I'm trying to troubleshoot a complex midi patchbay setup where I'm
sending from one Unitor 8 patchbay (#8 out) to a MTP II (#8 in). 

Help appreciated.

Neil