Pop-up ads are appearing on my desktop

If you’re not running your Web browser and are still getting pop-up ads on your desktop, you’ve most likely installed adware—a program that displays unwanted ads. Although benevolent adware exists, most of the time adware is up to no good. Getting rid of it isn't easy. “There’s a ton of little system-utility tools out there that promise to clean up everything, with names like PC Speed-up, PC Speed Pro, PC Speedifier,” Geek Squad’s Meister says. “A lot of times those programs are not going to do much. Some programs will work, others are snake oil.”

Avoid downloading programs that offer to speed up your PC or clean up your registry. Instead, use a trustworthy adware scanner like the free version of Malwarebytes' Anti-Malware tool.

Running a full scan with credible antivirus software is your first step. If that program doesn’t find and remove the adware, turn to Malwarebytes Anti-Malware Free, a great utility for removing all types of malware. Just make sure to disable your standard antivirus software before running it.
“Multiple antivirus programs working at the same time will often result in problems,” Falcon Northwest’s Petrie says. “You only want one active, real-time antivirus scanner installed, but it doesn’t hurt to run an additional ‘on demand’ virus or malware scanner.”
Searching online for the name of the advertised product can sometimes yield solutions from fellow victims. If all else fails, there’s always the nuclear option: a complete system reinstall. It might take a long time, but it’s the only surefire way to remove adware or spyware. Remember to back up all your personal files.