What can I do about pop-ups?

At this point popups are no longer a an issue. Modern browsers contain a popup blocker, which does the job the majority of the time. The unwanted popups that do appear now are usually an attempt to install malware on your computer. The popups appear as a message that your pc is infected. In many cases it is an animated GIF that looks like an antivirus application, which shows numerous files have been infected. In these cases you may disregard the supposed infection and close the popup. DO NOT click the X as it can and many times is a link to install the malware. You can press ALT+F4 until the popup window closes. If that doesn't work, go ahead and reboot your PC without closing anything.

After the browser is closed or your PC has been rebooted:

Many times when the browser reopens it will launch the same pages you had open previously. Close the browser or end the task on the browser process until the browser lunches the tab recovery window. At that point you can close the browser naturally or go to a new page, the malware infected page won't reappear unless you navigate to it again.