SIP speedo problem

Coming back from the VMSC rally the SIP speedo froze so I pressed the programme change button and went ok for a while then it went haywire. It change from one programme to another, at first I though it must be water got into the button but then noticed it also zeroed the distances on A & B. Finally it all went to zero with occasional flashes of speed and distance. I've not looked into anything yet but wondered if anyone has had a similar fault.