ok this is a crap shoot as MSDN does not doc these fully. So try them one at a time backing up the original value, reset after each change then if all fails, try them all at once.
Might sound odd, but some keys need other dependencies.
Note the last could be a security risk, so make sure to turn it off after testing the key. Let me know errors, issues or anything of intrest.
Also if it does work, try ad2p or BT headset if available to you.
[HKEY_LOCAL_MACHINE\Software\Microsoft\Bluetooth\pa n]
"ActivateOnBoot"=dword:1
[HKEY_LOCAL_MACHINE\Comm\ConnectionSharing]
"DisabledOnBoot"=dword:0
[HKEY_LOCAL_MACHINE\Comm\BTPAN1\Parms]
"ConnectionTimeout"=dword:30000
[HKEY_LOCAL_MACHINE\Comm\BTPAN1\Parms\TcpIp]
"EnableDHCP"=dword:1
HKEY_LOCAL_MACHINE\Software\Microsoft\Bluetooth\l2 cap
"NoRoleSwitch"=dword:0
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Bluetooth\Au dioGateway]
"NoRoleSwitch"=dword:0
[HKEY_LOCAL_MACHINE\Software\Microsoft\Bluetooth\pa n]
"Authenticate"=dword:0
-saridnour