Symptom: as engine/brakes warm up the brake pedal has less and less travel and eventually freezes up resulting in smoking brakes and a very short trip.
I first mis-diagnosed this as bad calipers, after new calipers, then followed lines and master cylinder. Each new step made no difference. Ready to throw in the towel, and actually take it somewhere, I stopped at Autosport to see Jon about it. After a few minutes of diagnoses, he pulled off my vacuum hose from the booster and dipped a zip tie down the hole - it came up covered in brake fluid! It turned out I had about a 1/2 cup of brake fluid IN my booster!

It now all made sence, I was convinced that the problem happened as the engine warmed up, with no relation to the brake usage - witch defied my logic and basic knowledge of the brake system. I had never thought of the old MC leaking into the booster.

just thought I'd share,
mike
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sometimes owning a 2002 can actually get you out of a speeding ticket( 2 and counting)
1976 2002
1978 320i (for parts)
1997 M3 sedan