I have finally managed to solve an issue that has been bugging me for a couple of months now, I thought I would share it with others that have similar problems, after all I have been helped so many times in the past.
My phone is a 6680, but it should apply to many other phones. I have been having very little success in connecting my phone to my PC. The wired link was fine, but Bluetooth was a no go. It worked around 20% of the time, which was probably worse than not at all. The phone connected to the Bluetooth headset fine, but the PC connection exhibited lots of problems.
Often it would sync between the PC and the Phone, but you could rarely browse the phone. Windows would sometimes throw an error that not all the drivers were installed. Sometimes if I booted the PC and the phone in the right order everything woud work OK. For a short while. I bought two bluetooth dongles thinking it was faulty. They were both the same.
Finally, after some research, I decided to give Bluetooth 1.2 a go. I think my devices were 1.0 (didn't know there were 4 versions until today). Anyway, so far it works like a charm. So if you are having these kind of issues, check are you using an older Bluetooth? If so, that could be your problem!