Early Windows Phone 7 powered HTC HD7’s appear to be suffering from a bug which can result in calls being hung up or put on hold.
Having been given the device at an O2 event yesterday (running in collaboration with the main Microsoft launch), ZDnet discovered proximity sensor issues. The touchscreen would remain activated while calls were being made, resulting in user’s inadvertently hitting the screen with their face, sometimes ending calls.
Apparently it’s a bug that should be fixed before the commercial release on October 21st.