Borg 386 said:
Also be aware that some fake pop ups claim you have a virus & it needs to cleaned immediately (by clicking on the button). Some of these look almost exactly like a legitimate windows Defender screen. They go the great lengths to make them look convincing/genuine.

Since it appears you may have adware, suggest you run AdwCleaner, which is good at ferreting out that kind of malware.

AdwCleaner Download

Here's one example of a program trying to impersonate a legitimate MS program. Looks pretty convincing, doesn't it?

Attachment 92015

Info & image found at:

Security Defender and Defender Pro 2015 Removal Guide
Always cracks me up when one of those pops up on one of my Linux desktops. Nice try!!!