Problems with External VGA Display in Vista, MacBook Pro



I've had this problem for a while - I'm trying to use my TV as an external display for my MacBook Pro (ATI graphics) when running Windows Vista. It is connected using the Apple VGA adapter, into the VGA port on the back of the TV. Vista recognizes that there is an external monitor attached, but no matter how much I fiddle with the settings, I cannot get an image on the TV - it just says "No Signal".

However, it works fine with the same cabling etc when I boot into Mac, and it even works when Vista is starting up - I get the boot screen, and then it just cuts out as I get to login. Also, it works in Vista with connected to a DVI display (but my TV doesn't have a DVI port, and I only bought it a few weeks ago - can't replace it just yet!).

As it works in Mac, I am assuming that this is some kind of driver problem with the BootCamp drivers (I am using the latest release of BootCamp off the Leopard disk). Can anyone suggest a solution to this, perhaps third-party drivers etc? (ATI says notebook drivers are the responsibility of system manufacturers, and so won't give me a download).

Any help much appreciated! Thanks!