Weird internet problem im experiencing

[Guest]

cant get on all the website except for one with firefox and internet explorer, but i can login to msn and steam and also play onlines games like mw2 and l4d2
a few days ago i opened up my computer everything was loading slowly on firefox and pictures were not showing, but then when i played mw2, i didnt have one single internet lag.
then the situation got worse now it doesnt even load.
plz help me

 

[sturm]

Run some spyware/malware scans
Malwarebytes and SuperAntispyware are two I use. Delete anything they find.
Also run a HiJackThis scan and post the output from it here.