Does anyone know of a Bluetooth app that allows auto-locking of a WinMobile PDA when it leaves the proximity of another Bluetooth device (such as a proximity badge)?

I work in a Medical environment, and the Docs want to start using transcription dictation onto PDAs, but don't want the inconvienience of logging in and out all the time.  We have to secure them somehow, tho, as we are responsible for patient privacy.

Thanks,

Boa1969