I have my Virus Ti hooked up to my Mac via USB. Logic Pro 9 set up with Virus as a 16 ch software instrument. All OK on its own but when I rotate knobs on my Moog Voyager synth which is connected via MIDI IN and OUT, i.e. it sends MIDI information when I turn a knob on the physical panel, the Virus patch changes in some way. Sometimes the filter, sometimes the envelope. I have to load the patch into Virus all over again and this keeps happening. If I unhook the MIDI OUT lead of the Voyager the problem disappears. Any ideas as to what I should do about this?