At school there is an HP laptop dedicated to doing presentations on the classroom projector once a week. Recently I changed the display layout from Cloned to Extended, with the projector as a secondary monitor.
That way I could have my notes on the laptop monitor while presenting on the projector. Afterwards I changed the layout back to Cloned using Intel's desktop context submenu.
Since I did that, the projector is not detected automatically anymore; even though in the Intel graphics dialog auto-detection is still enabled. Although I'm under no obligation to fix this, I'd hate to leave my not so technically inclined teacher with a quirky laptop.
The laptop runs XP. I'm at home right now, so I'm unable to check the exact model of the laptop or video card, but I'll post back with that information as soon as I can. Pretty sure it's 82865G based in any case.
EDIT: Between my asking this question and attempting the suggested solutions, the IT guys at school who explained to my teacher how to use the Fn key combos to enable/disable display cloning. She is content with that, so the point is moot now.