Annoying Pop Up (malware infection?)

You probably need to download and run a reputable virus scan program. I'd recommend Spybot and AVG--they're both free. There are some programs that advertise themselves as being anti-virus and anti-spyware when they are in fact viruses or spyware or malware themselves, and it looks like you've been infected with one of those. Good luck!

AHHHH!

If you keep getting this pop-up regardless of what site you are on, your computer is infected with malware. If it's Antivirus 360 or Antivirus 2009, then it's a really nasty one to get rid of (and often brings in some vile Trojans.)

First, get a good virus scanner, such as AVG. (I use Avira, both are free.)

If you do indeed have Antivirus 360o r2009, then you will need to get Malware Bytes. I have never successfully removed AV360/2009 without Malware Bytes. Luckily Malware Bytes is free and easy to use.

Right click on the little shield by your clock. If it includes the option to "Exit" do so.
Scan with AVG or Avira.
Scan with Malware Bytes.
Scan again with virus scanner.

MacAfee, Symantec, and Norton are no good against Antivirus 360/2009.

Then you will need Malware Bytes. You might be best unplugging from the internet while you scan. Help limit the number of virii invited in.

Good luck. With MB and a good AV scanner, you should recover from this.

But a sacrifice to the technology gods never hurts.