If I remember correctly it's the green top relay in the DME box. I swapped it with a spare I had and it has NEVER done it again. Just an idea.

It might very well tie into the EWS. It is designed to just cut the starter right?! I know on my E46 M3 it cuts spark and fuel. But I know that is different from most BMWs. Just want to make sure it isn't the same with the E53.

-Matt