Annoying sound distortion and lag when playing game

[89JeepYJ]

I downloaded the full game of Medieval 2 Total War and the demo for Empire Total War the other. Both played perfectly fine until recently. I started getting this annoying sound distortion and some lag whenever I would play. And it only got worse the. Even in the game menu, I would get the same sound distortion and lag. I was able to play The Battle of Pavia on high settings, perfectly fine, but now it is unplayable. I'm lost. I can't think of what would cause this. Those are the only 2 games I have so far, both with the same problem. My specs:

Acer notebook with 4th gen intel i5 4210u 1.7 Ghz Turbo boost up to 2.7Ghz (Its been running at about 2.4Ghz on M2TW.)
NVIDIA Geforce 840M with 2GB Dedicated VRAM
8GB memory.

[Squid]

Moved the thread to the Medieval II Technical Help where hopefully someone will be able to help you.

[89JeepYJ]

Moved the thread to the Medieval II Technical Help where hopefully someone will be able to help you.

I don't think this problem is exclusive to M2TW. Tried S2TW and I had the exact same problem. I think it has something to do with the processer and/or graphics card.