This message could be various problems.
If you’ve recently upgraded your DAW software, trash your OMS/ FreeMIDI Setup and build a new one. Also trash your Preferences/ default settings and let the software rebuild them.

Check your MIDI interface/ routing. Things like MIDI Echo/ Overflow and Active Sensing Filtering can cause the constant two-way communication between the HUI and your DAW to lock up/ drop out. HUI sends a constant MIDI note to remind the DAW that it’s there and expecting info.
And, of course, check all your cabling for loose/ backwards connections and/ or dying cables.