BMW 7 series E32 can't start when engine warm

Hi!
Few pieces of important information:
I have a 7series E32 3.0L .
I know my collant detector is spoilt. i.e. the unit which sits on top of where we pour the collant/water in. (Its cracked mainly due to age), so everytime I start the car I will have this warning coming on saying that I don't have enough coolant (eventhough I do! ). This doesn't bother me.

The problem I have in hand is... after the car gets hot/around the middle temp, or slightly above. and I turn off the car, and it CANNOT start!... until the car cools down.

I've changed my clutch fan recently so, there really shouldn't be anyproblems with the temp. Plus I don't get overheating problems.

What I think is that the car thinks that there is no collant and it won't start if the temp is warm. I'm not sure. I was wondering if anyone had any clues to this ?? Is there a bypass of somesort?

Thanx heaps!

When you say it won't start, do you mean the engine doesn't crank over [ no noise from the starter ], or does it 'crank-over' fine but just won't run????