Palm's just posted a software patch to fix a problem some users of the Treo Pro have encountered when using Bluetooth.
Here's what Palm has to say about the bug:
If you are in an active call using bluetooth car kit or bluetooth headset and you receive a second incoming call and you let it ring or you ignore the incoming call, the call will be diverted to Voicemail. The first call remains active but you can no longer hear the caller (the caller can still hear you). The audio has been lost. If you answer the call and swap between calls or reject the call, the issue is not seen.
You can download the Treo Pro patch here.
