Im on my Computer now: I copied the page
This is what worked on my 64bit system:
1. Install Windows Mobile Device Center:
Windows Mobile Device Center 6.1 | Windows Vista Support
2. The first step may solve your problem automatically, but it did not for me. So here we go: Right Click on Computer Icon and Choose Manage.
3. Go to Device Manager. You'll see an Unknown Device named Bluetooth
Peripheral Device. Double Click it to open its properties.
4. Click "Reinstall Driver" on the first tab.
5. Click "Browse My Computer for Driver Software" button.
6. Click "Let Me Pick from a List of Device Drivers on my computer".
7. Now the next page will show a list of drivers with Company Names in one list and Drivers in another. In the Company List choose Microsoft Corporation, not only Microsoft. Please confirm this twice that you dont choose Micorosoft but Micorosoft Corporation.
8. Now in the drivers list there may be one or more drivers with the name "Windows Mobile-Based Device Support" with different driver versions. I cant tell you which will work for you, but start with the newest version.
9. Click next. Ignore any warnings and keep pressing next and then Finish at last. If all goes well, the last screen will show the message that device driver is properly installed.