Hi JD45,
Acer are not a terrible make, personally I quite like a lot of the Acer Series we get 100's though our workshop. There not my favorite but there not utter rubbish. The problem you are having sounds like a hard ware problem not an inherent problem which is what you are making it sound like. If you had a problem with the keyboard and replaced it and worked fine (after the replacement) then that proves it was a hard ware fault, if it was a software problem the problem would still be there however because the problem has come back its probably due to the motherboard I would send it back.
The only inherited issue we have ever found with the Acers is the Speakers. I hope you get the problem sorted