Consider the following scenario:
a) You have a Bluetooth device with serial port profile connected after pairing via a USB dongle to a windows box.
b) You remove the dongle and insert on an another PC and pair it.
c) You then again remove the USB dongle and come back to first PC and connect the USB dongle. During this step, the blue tooth manager does not remembers the device. You have to
again pair it and exchange PINS to communicate with the device.
Why the Bluetooth manager is not remembering the connection? Is this an expected behavior? Is this a problem with the device or a problem with the MS Bluetooth stack?
When you pair the device with the first computer, a link key is generated that is used to provide authentication for your connection. Both the device and the computer stores this link key. Now when you pair the device with a second computer, a new link key is generated by the device and stored. When the device tries to establish a connection with the first computer, it tries to use the latest link key which is no longer valid and you have to go through the whole pairing process again. So this is not a problem with the Bluetooth Manager and the behavior which you are seeing is expected.