The engine 's suddenly death!

[Pongsak X5]

Hello everyone.
This's the first time i post in english, please forgive me for any mistaken.
I've lived in Thailand and just owning 2nd hand X5 3.0i year 2002 70,000 km. usage for 3 months ago.(it's very expensive here)

And i love it very much. Every thing 's fine until a few days ago while i'd ridden in the city , the speed 's about 10 km/h .The engine 's suddenly stopped . There're two signs showed on the board (battery charge current and engine oil pressure indiacator) . No problem to started it again.

Every thing is normal like it 's never occur before. It's only firtst and one time i've met. I've asked the former owner, he said that he'd just changed and use the same brand battery a couple months before and he 'd never met this symtom too, and the past history of this car is normal (except for tire, brake pad, and brake motor pump change) serviced followed the indicator light.

On that day i drove to the authorized BMW service center and they used the modic and said everything 's normal .

What can be the source, please advise me. Thank you a lot