Okay, I just recently paid SamAsh to re-set up my guitar, intonation, etc.
Before I took it in, when I played on my high E string around the 12th (and up) frets, the note would make this really annoying sound, it sounded like the sound wave was going super fast back and forth and the note would die out much faster then usual.

What I'm trying to find out is how to avoid that. Does it have anything to do with the tuning? If I'm in D, and I tune down to C will that happen again?
Any information pertaining to this would be extremely helpful since I'm not much on the "tech" side of guitars.
Thanks much!!!

You need heavier gauge strings, if you tune down that low with just 9's on ur neck relief will straiten and you'll get string buzz. If ur playing that low a lot get some 10's or 11's
Ah I see. I use to use Ernie Ball Not So Slinky but seeing as I'm 17 with little hands, it was harder to keep up with my music. I switched back to Ernie Ball Super Slinky and I think that is what caused it. If I switch to a different string gauge, do I need to have my guitar re-set up?
Depends what tunning ur in...A guitar thats been set up to play in E with a set of 9s on will play in fine in lower tunning is you use heavier strings because the tension is about the same. Heavier strings pull on the neck more than lighter strings so when you tune lower their still pull on the neck enuff to keep the relief the same.