Subaru Repair: Subaru dies, battery cables, tight connections

Question
My daughter's college room mate has a 91 Subaru that has died on her multiple times over the last few weeks.  The car radio, headlights etc all go dim or out and then car dies.  The battery will not run the radio once it dies as the battery is dead.  A jump will always restart the car.  The battery has been checked and the last auto zone tech put a new belt put on for her and said the battery was ok.  A shop in Atlanta even told her nothing was wrong with the car and they just charged her battery and sent on her way.  She then drove the car hundreds of miles to the beach and back without any problems.  Today the car died again.  Suggestions beyond checking the connections on the battery and both ends of the battery cables etc?  Thanks for the assistance!

Answer
OK..sounds like the voltage regulator in the alternator is going bad.. I have a 91 loyale that did the same thing.confirming the battery is good ..Change the alt..it will test good at the local store because they dont load the system..save yourself the headaches and change it with a new one...also make sure the cable connections are in good shape...clean/tight connections..is very important!..Have a great day! dan