Hello,
Couple a days ago, while surfing my desktop photo suddenly changed to a one saying that i had a spyware installed. I've checked my desktop properties and in the deskop theme menu the option "modified theme were selected". I've changed it but when i reboot my pc, it appears again at my desktop. Whenever i delete the picture from a folder "system 32" it generates a new one. Also I found a programm called "Anti Virus Pro" by "Atlant Develop Sl" which i never installed it before. I found out while browsing, that this software isn't reliable.
How can i permanetly remove it?

Configuration: Windows XP
Internet Explorer 6.0