Is it only occurring while you are using Firefox or all the time. Because, it looks like you have changed some settings on your monitor. However you may try this: http://www.paulstravelpictures.com/Dell-LCD-Monitor-Flashing-Padlock-Icon/index.htm

Can you attach a screenshot? *http://en.wikipedia.org/wiki/Screenshot *https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem *Use a compressed image type like PNG or JPG to save the screenshot *Make sure that you do not exceed the maximum size of 1 MB ----Do a malware check with several malware scanning programs on the Windows computer. *https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware Please scan with all programs because each program detects different malware. All these programs have free versions. Make sure that you update each program to get the latest version of their databases before doing a scan. *Malwarebytes' Anti-Malware:<br>http://www.malwarebytes.org/mbam.php *AdwCleaner:<br>http://www.bleepingcomputer.com/download/adwcleaner/<br>http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml *SuperAntispyware:<br>http://www.superantispyware.com/ *Microsoft Safety Scanner:<br>http://www.microsoft.com/security/scanner/en-us/default.aspx *Windows Defender:<br>http://windows.microsoft.com/en-us/windows/using-defender *Spybot Search & Destroy:<br>http://www.safer-networking.org/en/index.html *Kasperky Free Security Scan:<br>http://www.kaspersky.com/security-scan You can also do a check for a rootkit infection with TDSSKiller. *Anti-rootkit utility TDSSKiller:<br>http://support.kaspersky.com/5350?el=88446 See also: *"Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

Sashoto Seeam, You named the solution! It was a monitor issue! Thanks so much for the answer!