Spyware, viruses, & security forum: ZeroAccess trojan

That's not an error. That's a 'domain'.

Now please tell about your browser and the error.

Kees

I am sorry but I am a beginner and dont know a domain is; I am running internet explorer 9 delete failed

A google search for COOKIE "DELETE FAILED" leads to nothing. So either you have a rather unique problem or it isn't the exact message.
Can you tell how you try to delete that cookies (or all cookies) and what happens?

And what happens if you simply delete all contents from you cookies folder in My Computer or Windows Explorer (while not running IE)? Your cookies folder is (in Windows 7):
C:\Users\<your username>\AppData\Roaming\Microsoft\Windows\Cookies
Set the folder options to show both hidden files and protected operating system files to see that folder.

Kees

Perhaps reading http://www.donottrackplus.com/trackers/yieldmanager.net.php will help you understand what Kees was referring to. As stated, yieldmanager.net is a domain [that's the last part of an url] used by RightMedia which is an advertising company that is part of a network of sites, cookies, and other technologies used to track you, what you do and what you click on, as you go from site to site, surfing the Web.

You haven't shared much about the error with us. Or how it came about. Did you try to delete ALL your cookies? After doing so, did you try blocking yieldmanager.net along with yieldmanager.com? There may be a couple of others. You would have to search your cookies to see if others exist. (i.e. ad.yieldmanager.com and content.yieldmanager.com).

http://windows.microsoft.com/en-GB/windows7/How-to-manage-cookies-in-Internet-Explorer-9# tells you how to block cookies. It instructs you to click on the Tools icon, then Internet Options. When clicking on the Privacy Tab, you should see a "sites" button. Enter (and block) the first address above, then press OK. Do the same with the second. Does that help?

You might also want to consider scanning with the free program from http://www.superantispyware.com/ It detects and removes tracking cookies.