First post...been lurking around for years but didn't really have anything important to say.
I've been trying to get my laptop to connect to a ELM 327 device over Bluetooth. It worked perfectly with the available Android apps (that you can also find here) so I figured it would be easy to get it working with the ScanTool.net software on my XP laptop. Not so.
Long story short, the Bluetooth Support Service was starting under an account that didn't have permissions to create a COM port. The port would show up in Device Manager but wasn't actually working. I made a new Admin account and set the service to log on as that one, then uninstalled and reinstalled the Bluetooth dongle. Two COM ports showed up in Device Manager and I was up and running.
Also, Windows Firewall might be set to monitor Bluetooth connections. I don't know if this affects anything but it's worth checking into if you're having connection problems.
mods: I might have double posted...my bad...shady network connection out in the car...lol