I've been working on an issue for the past couple days that's got me scratching my head. We've got three identical HP laptop computers, ProBook 6065b, that used to function when connecting the VGA output to the projector on the ceiling in the auditorium. Now, whenever we try using the laptop with the projector, we get a BSoD reading "Bad_Pool_Header" (I can provide more details if needed on this error). However, I've tested another smaller, portable projector on one of the laptops and it functions normally using the same VGA connection. I've tried rolling back video drivers, installing new drivers across the whole machine, using msconfig to do a clean boot, tried in safe mode (no luck of course), virus scans to check for infections, etc and I'm running out of ideas. Called HP on this since it was happening with three of the same laptop and their best suggestion was to check the projector itself. We know this is working because another higher end HP laptop works fine with the projector in question, just not these ones.
On a side-note, if the VGA cable is connected to nothing and you try changing displays, it will also blue screen. If it's sitting on it's docking station and you try changing displays there (not connected to the projector we're having issues with) it works fine.