Cadillac Repair: electircal problem, battery cables, auto zone

Question
Hey, I have a 99 Caddy STS. I love the car and I'd hate to have to part with it.  My problem started about a week ago.  I got out of work and went to start my car and all it did was make a "click" sound.  After about 20 mins of not cranking the car finally started. Once started the car ran fine.  This led me to believe that there was a bad battery.  I took the battery to Advance, advance said that the battery was bad.  The next day I went to Auto Zone to get a battery (because it came from auto zone) and they did a battery test and said that the battery was good.  The guy at Auto Zone told me that the battery was fine and that he believes that it is a stater problem. (never got a new batter) I had a friend of mine who works for VW come over and take a look at the car.  He  found that if I kept the A/C and the radio off when I crank the car it cranks fine with no trouble at all. I rode like this for about 3 days. I still have no problem cranking up (so I don't believe that its a stater) Now when I crank the car up nothing electrical will work i.e. power windows, locks, a/c, radio and the dash goes black. About 10-15 mins after the engine is running all of the electrical components come on in the car and everything works fine.  If you can please give me some insight on the next steps I should take to resolve this problem.  Thank you in advance.

Answer
Check to make sure that the GROUND S (All black wires near the battery are all clean and tight. Also check the battery cables at the starter and the ground at the engine block as well. You will need, If necessary, Electrical schematics, Test procedures and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture.  I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information.