2001 Ford Ranger

I have a 2001 Ford Ranger with just over 100k miles. Truck was running fine, had to run and errand and turned truck off for about 15 minutes, when I went to start it, nothing. We tried to jump it, nothing, won't turn over, makes a clicking sound sometimes.
Also when the key is not in the ignition and I open the door the truck starts clicking really fast. Sometimes the lights work for a few minutes and then they go out.
I've only ever had to replace the ball joints on the truck, I've never had any other issues, excpet just a week ago I noticed a small leak around the oil pan gasket, but very small leak.
any idea's on what this might be, could it be the starter, or a short in the starter?
November 28, 2007.

I just replaced the battery and the truck is working great now! Thank you so much for the help, if anyone else has the problem try replacing the battery, if that solves your problem, please send in a donation to keep this site running!
Thanks again!

Nov 29, 2007.