[HUEY]

to be more clear:

By me (and I think also by fender2k1 as a read in an other post) it does not happen when switching sounds during play, but after switching sounds during play and then stop (or hit pause as fender 2k1 wrote)the sequencer. (in my case Cubase SX3)
By me it's not sporadic. I can let it happen in just a few seconds.

Even with the most simple setup:
1 miditrack in cubase with output "Virus Ti" on midichannel 1
4 full notes recorded and make a loop.
Press play, and switch sounds in Virus control (mc 1)and press the space bar to stop the sequencer or push the stop button in the transport bar.

In my case after several switches and stops it will crash

Hopefully we can sort things out

br