Maxima Forums - Car Won't Start

This must be my weekend for car issues. I have a 2002 Maxima with 140,000 miles on it. Since I've had the car I've had to replace the battery about every two years for some reason. A couple of months ago I got in it one day, turned the key, and nothing. Jumped it, but even when connected to the other battery it would get maybe half a turn before nothing.....it took a WHILE to finally get it started....drove home OK (at night, with headlights etc). Next morning when I came out, she was dead again. Used my girlfriends car to jump start it again, and drove straight to NTB because that's where I had gotten the original battery. They checked it and said, "Yup, you need a new battery.....no charge"....so I figured I was good for at least a couple of years....this was two months ago. Been starting right up ever since. Last night I unhooked the negative battery cable and let it sit overnight to clear the SES light I had still lit from a previous issue....went out this AM, re-attached the cable, and it turned the key.....nothing....no sound at all.....managed to get it jump started after a bit of work (again, even when connected to the other car it barely wanted to give me one crank before dying)....drove to the golf course, as I was pulling into a parking spot it died again. So much so that nothing electrical worked....couldn't lock/unlock the doors, couldn't put the windows up, couldn't use the key fob to open the trunk, nothing. Hooked up jumper cables to a buddy's car, and that was enough juice to lock the car up and get the windows up but not enough to start the car. Got it towed to NTB again after golfing....figured it must be the alternator.....no way the battery can be bad after only 2 months (right?)....but they checked the Alternator and it checked out fine....they are still trying to figure out what's wrong.....anyone on the ORG ever have a similar problem? Hoping for some help here. Thanks!