My electrical system shuts off while driving!

[cinnabar]

I don't think it's a battery problem but within the last few months the electrical system in my '97 shuts off completely while I'm driving. This has happened twice already while I was driving at night and it scars the H*** out of me. Most of the time it just shuts off for a second and then flicks back on but there have been a couple times when I can't get it to restart again and all the lights on the console are dim as if there's no juice and stays like that. PLEASE give me some advice on what to do. I'm about to take it in and have it checked out I just want to know what I should tell the mech.