Every now and then when I run Mission Planner, the airspeed indication is off by a factor of 100 (see graphic). If I restart MP, it changes back sometimes. I never saw this before one of the recent MP upgrades, but I've gone back to 1.1.92 and it still happens. This is in sim mode. I'll look for this the next time I fly in real mode.
My OS is Windows 7, 64 bit.
Hope this helps.