powewr draw?? problem

about a week ago i started losing the pre sets on my radio stations(57
beetle converted to 12v).when i would start the car i would notice the radio
eaither not come on right away or flash or dim when i turn on the
headlights(onetime radio came on but no headlights) for a few minutes.
i had a leak under the hood and some of the fuses were corroded i swapped
out the fuse block and new fuses in hopes that it would cure the problem
well the wife came home yesterday and said the car lost all power and died
(we have an alarm on the car were you have to touch a metal battery looking
thing to the flashing light before you can start it) alarm light starts
flashing and alarm started to go off,touched the button fired right up and
away she went,well it happened one more time on the way home
all i can tell for sure is that there is a definate power draw when i start
the car with the stero dimming ect..i am at a loss on this one electrical
stuff is not my strong point???
any ideas on where to start
i converted to an alt in the summer also has a 1year old battery.
about a month or so ago i swapped the headlights for halogens (not the super
bright ones)
does this sound like a ground problem?55amp can't keep up? i should also
mention that the battery does not have a problem has lots of power does not
turn over slowly even when the car died it fired right back up again.it is
like a breaker goes off and resets itself????
thanks russ