DNS Lookup Failed

i just tried yesterday to install a Kapersky Lab 2012 in my netbook and while installing it remove my MSE,i change from MSE to Kapersky because i was not satisfied with the results of MSE when someone inserted a 4gb usb stick and i suspected it right away it contains malwares,while scanning i saw a lot of ".exe , .pif" ..and i know those wer not part of her files because she didnt even care what was it and the results where NO THREAT detected ..my virus defintion is always updated and i also use a malwerbytes to recheck the scanning,but same results. >can anyone tell me why this WELL known scanners did not detect it?and now after installing a Kapersky..when trying to activate a 30 day trial first,it says "FAILED" and when i look in my status of my network it works fine. and i tried in a browser i receive now a "DNS look up fail bla bla" i tried Chrome and Firefox and i suspected i was being contaminated with that usb stick..so i used the Kapersky Virus Removal Tool 2010 and Dr.Web..which was suggested in my previous thread.it detected a few virus and hacking tools which is "CloseApp.exe"..but after 3 hours of scanning..still i coundnt connect to any website,but my network status is fine. i can send and receive packetdatas..also run the ping 127.0.0.1 and ipconfig but everything was fine.