Really funky electrical problems

Okay, I have read some other threads on part of my problem. Every now and then while I'm driving my speedometer and RPM needles shut off. After I either hit the dash or tap my brakes fairly hard, the gauges will then work again. Every once in a blue moon all the gages in the dash shut off, the oil pressure light, battery, gas and engine temp. The same thing, if I hit the dash it will turn back on. Some other forums have stated to remove the dash and see if their are any bad connections, like corroded wires or such. I was going to do that today just to see what I could find. But while driving to work this morning, I had my windows rolled down. I tried to roll them up, when I noticed that they werent working. Mmmm. Then I saw my turn signals were out as well I noticed that my radio wasn't working at all. The car was running fine. When I stopped, I turned it off and back on, and everything worked great. So, I decided to not pull the dash to see if I had bad wires for my dash quitting on me every now and then. Question is, is their a correlation between the two stuff? Does it sound major, or just wiring stuff? I did check all fuses, nothing wrong there. It is a 1998 i6, 4.0. About 93000 miles on it as well. thanx in advance