Let's see. Do a search for the three programs listed below. They are free and should help you out.
Panicware Pop-up Stopper
Also, take the time to make sure that you have your computer up to date. If you are running Windows XP, then you have the option of using Microsoft Anti-Spy and Windows Firewall. That includes Windows Update, and any other security related program that you have already on the computer. Check out www.majorgeeks.com
when you have a chance. There are all kinds of free downloads on the site that can help control threats like spyware, adware, pop-ups, trojans, worms, and viruses.