Guessing the 'system' is a sound system.
anyway. If it is a big amp, e.g high output wattage. It could be drawing to much current for your alternator as cmesld said.
Id say take it to a car audio specialist. Not autobarn or supercheap. And get them to diagnose the problem for you.
Shouldnt take them more than 30 mins if its something relatively simple like this
