We too have had numerous problems with the BT on 1.46 (also 1.45).
We have 4 different NXT's. The BT links to these 4 devices seem to work OK on XP/SP3.
On Vista, the NXT works reliably with one out of three VISTA laptops.
On Vista, with the recommended Microsoft stack and supplied dongle in the kit, two of the laptops can never connect. Usually we can pair the devices but then get a failure saying something like "NXT cannot be opened". Discovering devices is a total mystery - sometimes see it - sometimes not.
It appears that the pairing works, and the BT link and virtual com port are established, but then the RobotC to NXT communication doesn't seem to work and link is then torn down. We see the plug and play recognition of the remote device, then the installation of the virtual COM port, and then the error message followed by the disappearance of the devices.
We note that all working systems have automatically allocated a virtual com port of 6 and below (usually port 4 or below on XP) but our Vista Laptops often allocate ports from COM7 - COM16 and no working setup has been observed with a com port above 6. The only VISTA laptop that works is automatically selecting COM6
Based on our observations, I have a very hard buying that the RobotC-NXT link has been extensively tested on VISTA. Have you ever had it working through COM16? Does your test environment have multiple NXT's, multiple BT PC's, multiple discoverable phones, and other miscellaneous discoverable BT devices in range?
VISTA is not exactly irrelevant. Most Laptops have shipped with Vista for two years now and many if not most can't be upgraded
to XP due to driver or warrantee issues.
And yes we have reset everything although its not clear that everything actually gets fully reset. Sometimes, the NXT displays a different name than it reports during Bluetooth discovery. It seems that if you want to reset everything possible you have to:
Reset the BT on the NXT. (would be nice to know exactly what this does)
Powerdown the NXT.
Disable "Include BT in Brick Search" (see notes below) on link setup screen.
Remove pairing from each device if any.
Powerup the NXT and connect via USB
Select BT Factory Reset (would be nice to know exactly what this does)
Power down NXT
Power up NXT
Download FW to NXT
Power down NXT
Then you can try it again. Whether all of these steps is necessary is unknown. Whether a pinch of salt over the shoulder or facing east is also required has not been confirmed.
Of course, there are probably a dozen registry entries still left around from previous operations.
And yes, we have disabled WiLAN and this seems to have no effect on the problem. (A built-in WiLAN with a non-built in BT dongle will often have interference problems, especially as compared to a built-in WiLAN plus BT 1.2 solution.)
We have wasted much mentoring time on this and have now given up on using our team's VISTA laptops with RobotC. Since we have several vista laptops and NXT's we would be happy to test further if the existence of the problems were to be acknowledged.
BTW, on the link setup it seems to me to be very bad form to immediately enter Bluetooth discovery without explicit user action. It might be proper to attempt to connect to previously paired devices, but to enter Discovery (with its 30 second delay) should be something done only as the result of an explicit request (e.g. a Find NXT Devices button). We have at least a few hours wasted here (100's of attempts times 30 seconds).
Can anyone confirm a BT connection with a COM port above 6?