Pop up blocker stuck?

Your post has almost to none information at all in order to help you figure out what could be wrong?

Operating System and version?

Which program were you using when this happened and it version?

what hardware (PC) are you using?

In any case, when that happens again, and If you are a windows user, try hitting Ctrl+Alt+Del simultaneously and wait for the Task Manager to open up.

When it opens look at the lists of tasks, processes  and services that are running.

Identify which one is the suspicious process that is causing this unwanted pop-up behavior; select it; delete or terminate the process.

That is just a temporary fix. Find out where that program is installed and remove it from your system permanently.

Disconnect from the Internet and let your antivirus do a full scan and see if any weird stuff was found as well..

Can you take a screen shot of your program doing that and post it here?