Vista Tutorial - Blue Screen with Messenger Live, Vista 32 Ult, Nvidia vid card

I have been getting a blue screen when I use Messenger Live for about six
months. I am using Vista 32 Ultimate, several different Nvidia video cards
over this time period, Logitech Quickcam software with Orbit AF webcam.

The blue screen happens about 30% of the time, and when it does, it happens
at the beginning of the session, within a minute or logging on or so. There
is no relevant information I can find in the Event log, in fact, in the past,
the blue screen was not even captured in the log, just a note when the system
reboots that an unexpected shut down occured.

Lately, possibly because of a Windows update?? The system will bring up
Windows Error reporting after reboot to see if it can find the problem. But
nothing turns up.

I don't think it's the vid card, as I have used several, but they are all
nVidia. I suspect it's the webcam driver. As sometimes, starting my webcam
will crash the messenger application. What could be going on is a contact
may be requesting my webcam, and that causes the blue screen. But it is hard
to diagnose that.

I have heard that disabling the Messenger sharing service has helped blue
screens , but will that mess up my webcam?

Thanks for any help.

john