98 Altima Stops suddenly

Hi,
My 98 Nissan Altima Stops sunddenly, Car stops suddenly when its running. When I get the jump start of the car..it runs for some time ...and then it stops suddenly.....to start the car I cannot do anything.. I kept the car to cooldown for 12 hours ...after that also it was not start....it only starts after I do jump start from some car....and then it stops suddenly......
When the car stops, it apprears as if battery is goen dead, but I had replaced Battery 2 Months ago and got it checked once again after this problem..battery is working fine.....

Help Needed..

Thanks

its got to be the alternator then

its obviously the alternator, or the alternator belt, check all the belts in the car and test the alternator.

Its got to be the alternator. If it were the belt, you'd also be having troubles with cooling and power steering.