no power

i have a 98 BMW 323is manual. this started about one month ago,when i would start the car i would hear a click sounding thing from the front of the car before the motor started. Now i've had it where when i would try to start the car i hear the click then everything would go dead. i mean everything no light no radio the whole car is dead. but if i wait for like 5 minutes and try it again i got power and the car would start. This has happened a couple times and everytime i would wait around 5 minutes and go again. but today i unlocked my car and everything died.... i have asked a couple of buddies who said it might be the starter,a relay,fuses(i checked they look ok)bad ground somewhere. i checked the battery its good and clean. any ideas???