i am having the same exact problem. This past Saturday I went to crank it and it sounded like it was trying to crank but the battery just didnt have the juice to get it there, so i jumped it off and everything was fine the rest of the day.
I didnt drive it Sunday so Monday morning i tried to crank it and it didnt even sound like it was trying to crank. I tried jumping it off again to no avail so i thought it could be the battery. Took it to Advance and they put it on their machine and determined it needed replacing. So i bought a brand new battery and put it in and its still doing nothing. All the instruments, lights, radio, sirius radio, keyless entry are working, it just will not crank.
EDIT: I read where the alarm system can malfunction and cause the vehicle to not crank even when it has be disabled. Is this a possibility and is so how would i go about fixing it?