Grrr...
4.5.2 does the same thing. It's fairly clear the Virus synth and the keyboard are not talking at the same rate. Likely a serial interface not being clocked at the proper rate. Apparently Access knew about this problem. I wonder if anyone there still knows. Apparently the fix is supposed to be changing a crystal oscillator on the keyboard controller board. I can certainly handle that if Access will ship me the crystal or at least tell me what crystal I need.
I'm trying 4.5.1 right now but I think I'm probably going to have to go back to 4.0.7.