Vista Antivirus 2008: Why Can't I delete shwapi.dll and wininet.dll?

I've got that bad Vista Antivirus 2008 virus installed on my computer. I've gotten rid of a great deal of the stuff through various ways from tips I got from yahoo and just my own trying out stuff. But now I've come to two evil files: shwapi.dll and wininet.dll. I try to delete them but I get that dumb: "blah blah blah you can't delete this its being used by another person or program" message. So I use unlocker, and unlock, but then a screen comes up (well a little box) and it says something about memory error and it starts a countdown and then after about 40 seconds my computer restarts. Why is this happening? What else can I try to delete them? Please help me!