Is the car stock or tuned?
If tuned then to what level?
How many miles are on the car?
What where you doing before the engine cut out ie general driving, spirited driving or giving it a proper kicking?
I take it when you say it locks up but not sized dose it come to a dead stop or you encounter lots of residence?
Will the engine then turn backwards and free off?
What is the engine oil level and coolant level like?
Are you sure the was no out of the ordinary sounds when it ran briefly?