I am having a very similar issue Andy. I am using Win XP Pro SP2 w 2.5Ghz Intel Core 2 Duo processor running with 4GB RAM and a Novation Remote SL in Ableton Live. I have the Arturia V Collection and am running the Prophet V on VS mode. I am attempting to control the a,b,c,d OSC mixer but CPU is peaking (only VS loaded up) and then the mode switches back to V or Hybrid and back to VS as I try to control the joystick on the VS. Many errors with buttons changing color and such while I move the controls for the OSC mixer. This ONLY happens when I try the move the mixer joystick via MIDI. All other controls on the V and VS are responding OK. Very strange reaction to simple MIDI controller messages. My Prophet version is 1.2.1 released Jan 17 2008. I do not have this issue with my other VSTi. Please help!