Been a long time lurker on this forum. Own both the Sub 37 & Sub Phatty

Recently I've had a strange issue occurring on my Sub 37, which is causing my presets to change randomly.
When either plugged in via USB (direct) or MIDI DIN, the Sub 37 is constantly send out MIDI messages, and lots of them. I've run it through MIDI Monitor and posted a screen shot, so you can see what I'm talking about - these messages are coming through fast!
I've tried a few things to see if it stops. Firstly the Sub 37 isn't connected to a DAW, both the Moog and Mac have been turned off & on, and no other midi machines are running. I've executed INT SETTINGS, and reinstalled Firmware 1.1. - but nothing works.
Has anyone come across this issue?
Thanks
Andy