Bluetooth is still a relatively new technology when it comes to Windows. Although Windows 7 now has a reasonably decent bluetooth stack baked-in, it’s certainly not bug-free. It is not straightforward to control connection of bluetooth services, such as AudioSink, HeadSet, RemoteControl etc. And depending on how ‘dumb’ your bluetooth device is, your only option to get it connected to Windows in some cases (e.g. your device was last connected to a different host, such as your phone) is to completely uninstall and re-discover the device, as discussed on this thread. Weeeak.
I’ve written a small utility that may help with issue (it works for me, but I’ve only tested on my own bluetooth headphones – Sony DR-BT50). It works in conjunction with another utility I recently posted (that allows a program to set the default audio device), and provides control over connecting / disconnecting the available bluetooth services for all your paired bluetooth devices in Windows. It also provides a shortcut specifically for bluetooth audio devices which automates the process of getting a frustratingly silent pair of headphones / speaker to spring into life with a single click.
Download the utility here. I hope it works for you!