Ive had this latency problem for quite a while. Whenever i play CS or WoW in windowed mode, the game runs fine without any latency/fps issues. However, when I switch to fullscreen, I instantly start getting high latency spikes constantly (1500-2000 ms at times) and it makes playing impossible.. Im running xp, I have a wireless connection. I've tried with the wireless zero config enabled and all firewalls etc disabled.

What could be the problem? Has anyone experienced the same?

ive got some questions which might help me

does your fps also decrease? or is it just latency?
whats your graphics card?
have you tried switching priority settings?

Fps doesn't decrease. Just latency. Geforece8600GT graphics cards.. nope i havn't tried switching priority settings yet :/

well this problem seems pretty tricky to me, i cant imagine why would your latency in theese games suddenly increase when running fullscreen. I cant form any rational explanation for this. I dont think that visual rendering can affect latency

guys just donwload the newest drivers for yours video card! Reboot(Restart) your PC and everythink will be fine

There is good program called LtcyCfg(PCI Latency Tool v2.0).Sometimes with nvidia video cards the latency in computer goes high like 256,but with this program you can change it easly back to 64.There are other hardware too.I hope it helps.(best version is 2.0).It gave me like -45 latency in game and now it runs cs smootly

Thanks everyone for the help, now with updated drivers and the Latency Tool it seems i can play perfectly fine again :)

You're welcome:)