My desktop has vanished?

When i power my pc up i select my profile but when it comes on my desktop has vanished.No picture and no shortcuts.Just a white background.Fortunately its like the Start button has been selected as my documents page is open.Here i can get access to everything.So i ran Trojan Killer and it picked up 2.They had turned my firewall off.Once deleted the desktop came back,but now its gone again and so are those Trojans.I ran Spyhunter,Trojan Killer and Windows Defender(full scan)but got nowhere.This is on my wifes profile too.Please help