Okay, so I've already taken my friend out to the virtual woodshed after she drove her '88 740 until the entire inner plate of her LF brake rotor was ground off and the caliper subsequently fell apart. However, after replacing caliper, rotor and pads and bleeding the system, the brake seizes up when the lug nuts are tightened. If they're left loose, the wheel spins freely, with just a bit of grinding. Tighten the wheel properly, and it turns with steadily more resistance until it locks up, and the only way to free it is to remove the wheel. I can't see anything physically gumming up the works.

Any ideas, other than, "You should have let me change the pads two months ago when it FIRST STARTED grinding, M!!!" (Though, you can feel free to reiterate that to her too, and I'll pass it on)