battery/alternator problems

Ok, I recently went through two alternators, because they weren't putting out but 11.37V, when the battery had at least 11.95V with the car off. I condemed my old battery as the problem and went and got another, as soon as I installed it I checked the voltage, 13V off and 14.37 while running. Everything has been going fine for the past four days until this afternoon. I downshifted coming into a turn and the car cut off, I rolled to a stop sign and tryed cranking it. Nothing, didn't even turn over once, so I hopped out and measured voltage across the battery and found 1V to my suprize! I was pissed, after a good bout of cussing at the back end of the car I concluded that something had to be grounded. One of the owners of a nearby shop went and got me a boost pack and jumped me off, I got the car running and hauled ass home. When I got there I measured across the battery again with it still running and found 11.37V. At this point I'm thinking replace the battery and the alternator, I hate to throw parts at a car, but I'm so frustrated! Does anybody have any advice of what I should check? Any idea what my problem could be? I would really appreciate any help you guys can offer.

Thanks in advance,
Greg M