Sometimes the predictive nature of the stall warning system can, and most often does, go into flux and freaks out and ' runs home to mommy ' as jonesy puts it in the Hunt for Red October. The CRJ200 has a limitation, which is correct, that when you are vref flaps whatever +17 you need to avoid operation with spoilers deployed and flaps greater than 30. The aircraft can be safely flown in this regime, only very carefully and any deviation or large control inputs will result in the stick shaker momentarily activating.