I had a problem with CSR bluetooth 4.0 dongle and with its own software. It worked just fine until I restarted my pc. After that it just wouldn't connect to anything and did not even re pair with any of my bluetooth devices. I had this problem about 1 year and I finally found out a solution. Now I would like to share it in here, because I have found it to be a common problem.
I figured if it was a driver conflict with csr drivers and windows bluetooth drivers so I opened device manager from winkey+x menu. Then I selected bluetooth radio and delete driver (all of them bluetooth drivers), then I just installed manually CSR drivers (don't take bluetooth dongle out from the usb port and do not restart your computer before!) And like magic the problem disappeared and it has worked just fine after doing that. It has been over a week and it does work like it should have been from the beginning. Now I feel a bit stupid because the solution was so simple after all.
I really hope this helps everyone.