key stuck in ignition. everything in car shuts down/dies. how do i stop this?

I have a 2007 chevy cobalt lt. when i go to start my car, sometimes when i
go to turn the key in the ignition, it stops about halway through, locks my
key in the ignition, and shuts down everything in my car, and i cant get the
key out. everything dies... lights and all. i have to go into my trunk and
touch a needlenose pliers to the positive end of my battery repeatedly until
it sparks numerous times and my trunk light comes on and stays on without
me touching the battery. when i get it turned back on, ill put in in drive,
push the gas, my rpm's go up and my engine revs but i dont accelerate or
move for a few seconds and then i start moving but it will cut out every
once in a while while im driving. does anyone have any ideas on why it
does this?