Hydorgen Sulfide and Copper Electric Circuit

I live in Louisiana and have the Knauff Chinese Sheetrock throughout the house. All my electrical copper wire is black where it terminates in wall switches and outlets. When the house was built in 2006, I had to go into every outlet and wall switch and tighten the terminal screws so that contact was firmly established. I had some outlets that went “dead” after putting a load on the circuit (i.e. plugging-in a lamp or coffee maker). They would work for a second or two and then went “dead”. The only other problem that I have is that some of the light switches sound like they are frying for a second or two when I turn a light switch on (or even when turning the switch off). I’ve had some electronics fail in the home and even had a 55" projection t.v. fail six months after purchased new. Is there any danger if the terminal ends of the wire is black (not corroded). Thanks in advance.