The virtual keyboard does not send MIDI! :-(

This is sooo annoying, I hope that this is something I have done wrong so I don’t have to take it out on Steinberg.
Well, the title says it all. Sometimes the Virtual keyboard (alt+k) just stops sending MIDI information to the VST plugged on the track. I can play with my mouse directly “on” the, let’s say piano keys, but not using the virtual keyboard with neither the mouse or keyboard commands (qwe etc…).

When I’m away from my Midi keyboard I use this alot, so it sucks bigtime when it suddenly won’t work.
:smiling_imp: :smiling_imp: :cry: :cry:

EDIT: I deleted ALL my preferences (on a Mac) and now it’s working again, but what causes this?
Really want to know, so I don’t have to keep on deleting preferences all the time…

Are you sure it’s not a focus thing? When it happens again, try just clicking on the VK to see if bringing it back in focus sorts it.