Can some sound systems wreck your car's electrical system?

Not very likely. Why do you ask?

The car shop said my electrical system was all jacked up because of the sound system I was using. But many of the problems they listed I had encountered before I put it in my car. The sound system is a small one meant for TVs and computers but it plugs into the car for power. Would it be the electricity usage or the sound frequency that they are blaming for all the problem?

Yeah, an aftermarket stereo can do all kinds of things to the electronics.

The electricity. You should have had a high capacity Alternator and a designated circuit.

Ford windstar,s are known for having bad electrical issue,s,right off the bat,mainly 1998-2002,the radio you are useing,may be adding to it by drawing power,but it is not the radio doing it,it is the van it self,