Hi Christina -

The issue you described does not appear to be the result of Yahoo! advertising. It is possible that your network or computer has been infected by adware, spyware or a virus. Adware and viruses can be installed on your system without your knowledge. They can cause exactly these kinds of symptoms. They can even affect the way your computer looks up Internet addresses.

If you have not scanned your computer for spyware and viruses, we strongly recommend that you do so now. Spyware programs can change your system settings, serve pop-ups, record your surfing habits, or display advertisements. Certain spyware programs and computer viruses might run separate programs on your computer for a variety of purposes. These programs can slow down your computer sometimes. They can even prevent you from accessing Yahoo! or other Internet sites by redirecting you to other pages or by displaying error pages.

You may find the following article informative:

   Yahoo! Security Center - get rid of pop-ups

Let us know if you have any other questions and we will assist you as much as we can.

We appreciate you choosing to use Yahoo!

Nixon