Do a malware check with several malware scanning programs on the Windows computer. 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:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked
• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/

I thought this was fixed. I've used many of the above tools with no malware problems. I thought I might have found an issue when using ADWCleaner in the Firefox area, but after clearing those out, I'm still having this security message pop up occasionally. A simple google search shows this problem has been coming up once in a while for a long time and is usually attributed as a software bug in Firefox. Any ideas?

Please provide a screenshot of that message.

https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

It is best to use a compressed image type like PNG or JPG to save the screenshot and make sure that you do not exceed a maximum file size of 1 MB.

Then use the Browse .... button below the Post a Reply text box to upload the screenshot.

Here's a screen shot of the error message.

Here's a possible thing in the Firefox section of AdwCleaner that I deleted. Did a similar delete yesterday....

When that "Alert" appeared, were you trying to open the email which was sent to you from this forum - which was notifying you that an answer had been posted to this thread?

If that is the case, we may need to get an Admin involved in this discussion as there might be a problem with AOL and the formatting of the email being sent out from this forum.

As far as that AdwCleaner screenshot, I suspect some Babylon Malware is on your PC and AdwCleaner is labeling that as a "user-set" preference. Do you want that Babylon 'stuff' on your PC, or do you want to get rid of it? If the latter, see this - https://support.mozilla.org/en-US/kb/remove-babylon-toolbar-home-page-and-search-engine

Or this - http://malwaretips.com/blogs/remove-babylon-search-virus/

Website servers can send a specific HTTP response header to prevent injecting code in web pages and only allow content coming from their their own server.

• https://developer.mozilla.org/Security/CSP
• https://developer.mozilla.org/Security/CSP/Introducing_Content_Security_Policy

I wasn't trying to open an email when it popped up. It usually pops up when I'm reading the Android Central HTC M8 forums...only on Firefox. I will go through and get rid of any Babylon stuff. Don't think it's causing the problem...but not sure.

Website servers can send a specific HTTP response header to prevent injecting code in web pages and only allow content coming from their their own server.

   https://developer.mozilla.org/Security/CSP
   https://developer.mozilla.org/Security/CSP/Introducing_Content_Security_Policy 

This problem just started after the last two Firefox updates. I use the same websites everyday and have for a long time.