Try the following fixes:
Wallpaper Hijacker Removal Tool:
http://www.majorgeeks.com/Wallpaper_Hijack_Remover_d4816.html
Note: You should hit all "Repair" buttons even though it may not say "Found!" This will fix a wallpaper hijack everytime if all repair buttons are pressed.
VundoFix:
http://www.symantec.com/content/en/us/global/removal_tool/threat_writeups/FixVundo.exe
Disconnect your computer from the internet
Run vundo
Restart your computer
Run the tool again to ensure no traces are left.
If there are the reboot into Safe Mode and run FixVundo again.
SmitFraud Removal
This tool will remove Desktop hijacking malware. Firstly, download the removal tool from here:
http://downloads.securitycadets.com/SmitfraudFix.exe
How to use:
http://cotojo.wordpress.com/2007/08/24
Malwarebytes Anti-Malware Removes Antivirus 2008/2009/XPAntivirus and many more:
http://www.download.com/Malwarebytes-Anti-Malware/3000-8022_4-10804572.html?hhTest=1.
Download, install, update and select Full Scan.
Remove all infections that it finds after scan.