I have added a text input field to my application. It is supposed to show a virtual keyboard when an input field is touched. It actually works fine in the simulator, but touching the input field crashes and reboots the physical handset. (A Dopod F3188, basically the same as HTC Smart.)
It looks conspicuously similar to the virtual input problems discussed here as well as another discussion, where the sample application crashes on the HTC Smart.
This is a known problem with some versions of the firmware for the HTC Smart. Either upgrade the firmware on the phone, or do not call IWidget_EnableVirtualInput(), which is what crashes the phone. The solution has been added to the Brew MP forum threads.