Trojan Horse guarantined; wifi connection is whacked

Recently (2 weeks ago), I had been infected by the Trojan Virus because my younger brother tried downloading a game from the internet. My laptop restarted, notifying me that everything was restored to normal after Symantec AntiVirus quarantined the Trojan. Everything went back to normal and I haven't had a problem until last weekend.

My laptop's wifi adapter says that it is connected my families wifi connection; but after using firefox (and i've tried IE too) for around 3 minutes, the browser stops detecting an internet connection. Itunes also did not detect my home wifi but somehow, Skype does. More strange, all of the application I mentioned work fine with my neighbors wifi connection. So I have the feeling that there is something wrong with my ip address configuration.

Hence, I did "cmd" in run and then inputted "ipconfig" but nothing came; so i started to think that the trojan horse might have messed up my ip address. So, I headed over to MajorGeeks.com and ran almost all of the tests recommended (except for downloading the 5 different anti-malware programs because I didn't know some of the programs).

The good thing is: my ipconfig input works fun for command prompt but my internet connection is still whacked.

SO...now I want to know what is wrong. I deleted the Trojan Horse guarantined as needed and other malware but the problem persists, and also ran TrendMicro Hijack and went through the list getting rid of things that were bad (recommended by Major Geek) HELP!