Unistall you anti virus, or go to quarentine, and delete crossfire.exe Than turn off you'r anti virus, than re-install crossfire.
disable your antivirus and go to your guarante and restore it if you cant restore it reinstall the cross and have allways disabled your antirus
Obviously reinstall crossfire, and get another antivirus. or try to download this Virustotal Jotti Malware scan