VirtuMonde is an adware program that downloads and displays popup advertisements. It may also hijack the browser to unwanted advertising related sites.
There is a free removal tool offered by Symantec here:
http://securityresponse.symantec.com/avcenter/venc/data/trojan.vundo.removal.tool.html
Follow the removal directions on the download page. Run the tool twice with a reboot inbetween to be sure it got everything.
