Launch your anti-virus protection software and update it to keep the virus and spyware definitions current. This will vary depending on the anti-virus program you are using. If you don't currently have an anti-virus program, look into effective and well-rated anti-virus programs such as BitDefender and BullGuard10.
Run a full system scan and remove any malicious cookies and rogue files found.
Navigate to the C:\Documents and Settings\username\Cookies folder and delete the ad.yieldmanager cookie. Empty the Recycle Bin.
Alternatively, delete the ad.yieldmanager cookie by launching your Internet Explorer Web browser and clicking "Tools" on the main menu.
Click "Internet Options" and click the "Settings" button by the History section. Click "View Files." A new window will open with cookies and browsing history.
Right-click the ad.yieldmanager cookie and click "Delete." Click "OK" to save the changes and "OK" again to close Internet options. Empty the Recycle Bin.