Nice one Carl, which post was that?
Assuming then that solo and mute issue is not a known issue you could try:
Disable - Share drivers with other programs (precaution)
Disable - Allow arm changes during playback/record (even though it may appear unrelated).
Like I said had a similar issue with mute/solo and it turned out to be my drivers (and we don't know what you are running, or if your steps to reproduce are indeed similar to mine).