I have two Windows 7 PC's at my desk. I installed a Class 1 Bluetooth adapter on the first system, and was able to connect to a mouse using the Add Device option in Devices. It worked pretty smoothly.
The second PC (Windows 7 just like the first) is not playing nicely. The adapter is installed with no errors in device manager. When I go to Add Device, the mouse is not shown/detected.
If I click the Bluetooth icon in the taskbar, I see the bluetooth mouse (which is turned on with fresh batteries). This is what appears when I attempt to pair:

Why is this happening on my second Windows 7 machine? Where do I find the Bluetooth Passkey?