Download Hijack This and the Hoster program. Open Higjack This and run a scan. You can download them from here. http://www.bleepingcomputer.com/files/Merijn/hijackthis_sfx.exe
Find the entry below and check it.
O4 - HKLM\..\Run: [WildTangent CDA] RUNDLL32.exe "C:\Program Files\WildTangent\Apps\CDA\cdaEngine0400.dll",cdaEngineMain
Click Fix Checked.
Delete Wild Tangent if it shows in Add/Remove programs.
Open the Hoster program and click Restore Original Hosts. Click ok or yes for the prompts and close the program.
Show all your hidden and system files through My Computer and delete the C:\Program Files\Wild Tangent folder.
Reboot.
Wild Tangent is an adware that causes pop-ups. It is a real pain but this should remove it.