Googleadservices (and other sites like clicksynergy) blocked

Question

About a year ago I downloaded a list of blacklisted sites that would cause safari (and, apparently, Chrome and Firefox) not to open ad links in Google, etc.  This has become a minor annoyance, particularly because I can't remember what list I downoladed or how to disable it.  Does anyone have any idea what I might have done!?!  I know it was a .txt file that redirected the ad url to somewhere else.  I think it was to the local url.  (If that exists.)

Answer 1

You have a modified hosts file.
By far the easiest way to fix the hosts file is to restore it from a Time Machine (or other) backup that predates the modification. If that's not possible, then do the following.
Back up all data if you haven’t already done so. Before proceeding, you must be sure you can restore your system to the state it’s in now. If you skip this step, no one but you will be responsible for the consequences.
These instructions must be carried out in an administrator account, if you have more than one user account.
Select "Go to Folder..." from the Finder menu bar. In the text box, enter "/etc" (without the quotes.) A Finder window will open on the "etc" folder.
Double-click the file named "hosts" in that folder. It should open in TextEdit. At the top of the file, you should see something like this:
# Host Database
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
127.0.0.1                              localhost
255.255.255.255          broadcasthost
::1                                        localhost
fe80::1%lo0                    localhost
Below that, you'll see some other lines added by you. Delete everything below the last line shown above. Make sure you scroll all the way to the bottom of the document. In Lion, scroll bars are hidden by default until you actually start scrolling, so you may not realize that you’re not seeing the whole document.
Don’t try to save; you won't be able to. Instead, duplicate (in Lion) or select "Save As..." from the file menu (pre-Lion.) In the Save dialog, make the name of the file “hosts” and deselect the option to add a ".txt" extension to the file name, if it's selected. Save the file to your Desktop. You should now have a file named exactly "hosts" with no extension on your Desktop, having the contents shown above.
Now launch the Terminal application, for instance by entering the first few letters of its name in a Spotlight search. Copy or drag -- do not type -- the line of text below into the window, and press return:
sudo sh -c ' cat Desktop/hosts > /etc/hosts '
You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up. Confirm. Quit Terminal.
Do not type anything into the Terminal window except your password.
That will fix your hosts file. You can now close the “etc” folder and delete the hosts file on your Desktop.