DNS Lookup errors all over the place ...

This thing has been bugging me for well over half a year now and I can't seem to fix it.

The problem is like this:

I'll be playing an online game, or downloading something or surfing when suddenly, my connection drops. Sometimes, it takes a second or 10 for the connection to come back, at other times, the little network icon in the lower right gets a yellow mark indicating something is wrong and my connection drops completely. I can fix it by disabling and reenabling my ethernet adapter OR by choosing "Troubleshoot problems". The former I only figured out a month or so ago and is quick - the latter I've used since I got the problem. Then Windows will fix it and will say something about resetting something involving DNS.

Since then, I bought a USB ethernet adapter but that didn't fix it. I've tried setting a manual DNS (8.8.8.8) which didn't fix it either. I completely reinstalled Windows since I first got the problem (for a solid state drive) so the problem wasn't fixed by a reinstall. And when I had DNS problems on my PC, my phone hooked on wifi to the same router kept working perfectly so I don't think it's router related.

I'm honestly out of ideas here. The USB ethernet adapter I bought today after hearing the problem was common with my motherboard so I figured it was the ethernet chipset but it's obviously not - the problem persists. Anyone have any idea what to do?

Windows 7 Ultimate 64 bit
8GB DDR3
INTEL CORE I5 2500K
ASUS P8P67-M DDR3 P67