Serious sound stuttering, input lags.

Hi!

I have a serious sound sluttering / input lagging problem (again). I had the problem months ago, the "evil" is back. Don't know, what solved my problem last time, so I have absolutely no idea, how to solve it. I can't listen to music on my PC. (Even with low CPU usage and low HDD activity. It just drives me crazy. Sometimes, the sound stutters for 0.5-2 seconds! Which mean, my keyboard does nothing, my mouse does nothing, then it works again. It happens like in every 5-30 minutes, it is totally random, if the computer has higher load, it is often, but sometimes, with 2-8% CPU usage this happens.

Temperatures:
Samsung HDD (160GB): 38°
Western Digital Caviar Green (250GB): 31°

Intel Pentium D 925 both cores: 41 C°

GPU: ASUS Radeon HD 2600XT core temperature: 30°

(These temperatures are the current ones, and there was so many lags while I wrote this post.)

I'm a little bit suspicious about Netlimiter. Can Netlimiter cause that problem? (I'll uninstall, curious about the result.)
Netlimiter3 has been removed, problem NOT solved, I'm frustrated a little bit, I'm out of ideas.