Try increasing the Debounce Interval (Config. / General Config.) to 2000 or so.
If this reduces or cures the problem then you need to look for the source of the problem which could well be electrical noise pickup from your Inputs wiring. Check that good quality, shielded, cable is being used and that the shield is connected to Earth at the controller end only - also check the quality of your switches and perhaps fit a 0.1uF miniature capacitor between each used Input and Earth at the controller end.
Also, as Russ said, make sure 'Use WatchDogs' is unchecked (Config. / General Config.)
Hope this helps.
Tweakie.