car goes dead when try to start
 

in my focus, last couple of days, when i turn the key on, it goes to ignition fine, all lights come on. then on the last turn to start the engine the whole electric system cuts out. it wont start, lights go off, when i open the bonnet i just hit the battery cover and all the electric comes back on, go in and normally i can start the car. however cd player reset, clock reset etc.

know, i know there may be a bad connection on the battery, the part that connects to the battery, one end is broken and therfore may not be mega tight on the conection, but it is on. also why would the electrics initially come on, but then turn off when i try to start the car.

any opinions on what it could be?

cheers