printer and Trojan

Lan, maybe reinstalling Windows will actually help...

Viruses can't be removed this way!

I have Avast! Plus, I also downloaded and ran a one-time Dr.Web scan yesterday... but there are no viruses, no matter what!

Avast is good, especially when you install mods on it; it will protect you like a rock. Web is a terrible antivirus (sorry for the expression); never use it (I used it to scan my computer and found only 5 viruses, while AVP found 1000 – believe it or not). Download NOD32 and update it instead!