Crashes when midi is plugged in

This morning, switched on the system and a track I am working on. When I have my mid gear switched on when I select a midi track, the system completely freezes up. When the midi gear is all switched off, everything works fine when selecting midi.
Any ideas what is happening here?

Ok… have fixed this issue by restarting the Midiman 8x8s. This thing can be a bit problematic I find.