Hijacked My Pc?

My situation is this, my computer cannot conect to the update of Antivir, My Internet Explorer its been acting very funny, sometimes I cannot make my favorites to appear, and the shorcut of a link of Internet of Sympatico MSN, canot be displayed, I reall.y need some help here , somtimes I get like a flash on the cornerup right of my monitor, when I turn off a page of Internet Explorer.
I cant make with double click , of the mouse appear even a notepad in my desktop !!
I been Hijacked !!?? someone is in my computer? from far?
My roomate downlad a patch for a game, today when I return from classes , she told me that teh computer start acting pretty badly, I realy dont know how long, Im gonna be able to control mu computer, I check first my computer and its was a Trojan URL blank.
So I perform teh remove Instructions for teh reg. infected, but this time its been far from my knowledge of Fix. I can post a hijack if required , righ tnow I scaning with antivir removal tool 3.0 but I dont know it, going to work .