Strangest electrical problem ever...any suggestions?

[Budarooski]

This has happened three times now and today required I get my car towed...not happy.

If my 2007 X5 4.8 is in slow moving traffic or left idling for 20-30 minutes it will lose all electrical power and shut off. First the ABS warning light comes on, then AWD warning, then transmission warning, then the A/C shuts off, my radar detector will show "low voltage" and the car limps along stuck in one gear until it dies.

Each time it occurs, it's after being stuck in slow moving traffic for 30-40 minutes. The battery is brand new and three weeks ago a specialist looked at my car for four days...no codes, alternator checked out ok, battery ok, and every module tested ok.

The weirdest thing...today when it died, after waiting 2.5 hours for a tow to the dealer, I pushed the start button and the started right up!! So I drove it to the dealer (I was already on my way there to address the suspension air bag leak).

Clearly something is getting warm and causing an electrical problem...when the car cools down it starts up again. The shop manager at BMW said it's probably the alternator...which makes no sense because a) it was already tested, and b) the car started up again when it cooled down after losing all power...batteries don't recharge themselves.

WTF is going on with my car???? So far this summer, over $6K in repairs (oil leak, coolant leak), $2K for new tires, $400 for new battery, and now this air suspension and electrical problem...I'm sure this will cost me dearly. To say I'm pissed is an understatement.