Adapter powers up, gets detected, then disappears

I have a Dell laptop running Windows XP SP3. I recently replaced the Medialink Bluetooth adapter with Plugable’s adapter. When I insert the adapter into a USB port, it powers up and the system reports finding it and tells me it is ready to use. But then the adapter goes dark. If I run the Broadcomm setup utility at that point, it fails to detect a Bluetooth device.

The adapter works fine on my new laptop (Win 8.1).

The WinXP laptop reports that all USB system components are functioning properly.

I don’t see any Bluetooth-related software to uninstall! The Medialink adapter also used the Broadcomm stack, so I *expected* not to have any driver issues with the Plugable adapter.

Ideas, anyone?