We’re aware of crash issues with SwitchEm and devices running iOS 3.1. Unfortunately, those issues were caused by a mistake I made in setting up the executable for distribution. My fault, and I am sorely embarassed.
The good news is that a fix is coming very soon. Until then, please be patient with us and accept our heart-felt apologies. Fortunately, we will not be requiring an update to iOS 4. That would be easy for us, but not good customer service.