Help with minor lagspike while kreedzing

Hey guys ive been playing around on my LAN server for some time now and recently i start to feel this wierd 1 sec lagspikes which usually stays for around 1 sec before dissapearing for another 5-10 sec then it starts all over again while playing its really really hard to explain in words so i made a clip and put it on youtube for you guys.

Youtube Link : http://www.youtube.com/watch?v=9pwu84JTPLw

I have already used google, played around with rate in-game also played around with my gfx settings aswell as CS video settings with Software / D3D mode different resolutions etc changed my hl.exe processor priority to lowest / highest. Also note that i havent seen any fps drop what so ever while having thoose lagspikes. Im always on 99-100 fps. I also been searching my computer after virus, but that shouldent be the problem since my computer is brand new.

I got the latest drivers for my GFX card aswell!

Please remember this happens on my LAN server and never while playing online which makes it EVEN more wierd
Also restarted computer several times... I also got CABLE internet and not any wireless shit :p

And yet nothing have solved this problem. Any advice would be VERY much appreciated!

My computer specs:

GeForce GTX 460 768MB

Corsair XMS3 DDR3 1600MHz 4GB CL9

AMD Phenom II X4 955 Black Edition
Quad Core, 3,2Ghz, AM3, 8MB, 125W

ASUS M4A87TD/USB3, Socket-AM3

Windows 7 64-bit's

etc

// Peace out. bob

yeah pretty annoying, they can really fuck up any run.. :/ the problem first came after i installed kz-demo plugin. I removed it now but its still there so dno what to do really.