Pc crashes in almost every game I play

Ok here we go,

I have a computer that I built, that after almost 2 years is starting to have some problems. A while back I installed Kaspersky AntiVirus and the computer got locked up, what I was told is that it deleted a Windows critical file... not allowing the computer to start windows. Anyways I took the computer to my local computer repair and the guy removed Kaspersky allowing the computer to work fine...
About a week later during wow my computer got a couple blue screens randomly... but would turn back on normaly. Also WOW would crash every now and then giving me error 132. I called Blizzard tech and they told me to do all of these things and if they didn't work then my memory was bad. So I did all of the tweeks and then did the windows memory diag, for almost 10 hrs... no errors were found. So my RAM is good then I assume. Anyways after getting frustrated I got onto Battlefield BC2 and then Punkbuster will kick me off almost instantly... every time... Not sure what the cause of this is... but probobly related. Does anyone have any idea what this could be, Thanks.