My CS200 "pauses" when I stop moving. Like when I'm at a stop sign. It didn't do that tricky thing before I installed the speed sensor (had the rest installed for a few weeks before I installed the speed sensor). It does continue to display cadence (at zero) and heartrate while it is "paused"....

Maybe try removing the speed sensor and see if the problem stops...You might just need another sensor or maybe your wheel magnet is getting a little out of whack and the sensor can't pick it up sometimes?