97 nissan p/u, bad ground?

[cplstew]

97 nissan pu, 4cyl, 5spd, 4+4, 80,000 miles.
this problem does not happen all the time, but when it does, it happens repeatedly about 4 or 5 times, all the interior lights, radio , blinkers, turn off, and gauges go down, when I turn on the blinker, or press the brake, or just from accelerating or hitting a small bump in the road. The headlights stay on and there is no disrruption in the eng. and i have to turn the radio or blinkers back on to get every thing to turn back on. I know the power is getting shut off completely because the radio gets totaly reset, I've been told it is a bad ground and that it might be the computer, how can i identify and fix the problem, or how much do u think it will cost to get fixed.
please help, its really annoying to have to set me presets all the time.

[zkor1]

Sounds like the ground wire from the battery.