with a probability of 99%, it's malware. Try a good antivirus program. It can be tricky to remove that without further information and/or direct access to the computer. Unfortunately, there's nothing you can do from within firefox to prevent this from happening, because most likely it's an external program hat re-enables anything you disable.

edit: deleted

I run MalwareBytes premium daily doing as complete a scan as it does. Any suggestions for a better antivirus program?

It's primary a religious question. Though some are better than others, in america you may want to use bitdefender instead of kasypersky due to conspiracy theorys of kaspersky and the russian secret service. in germany, avira antivir is a good choice. concerning the features, kaspersky is the best i know. avira antivir has got the best detection.

It's possible that your antivirus doesn't know the malware yet. In that case, you will have to wait or try another antivirus, then do a full system scan. You could also try scanning your pc in safe mode, which is a great feature of malwarebytes.

another way is to try removing it manually, but i can't give you advice with that because it's different from virus to virus. If everything fails, I can look at your PC using teamviewer, but without promising anything.

p.s.: http://uk.pcmag.com/malwarebytes-anti-malware-20/3774/review/malwarebytes-30-free here's a good test of malwarebytes.

This could help with the issue: http://filepony.de/download-frst/ and for 64-bit: http://filepony.de/download-frst64/ it will create a logfile that can be analyzed without direct hardware access.

It's also possible to check for a mallicious addon (but most likely, the malware will reinstall it) and disable it. this is how to do so:

"Go to the 3-bar menu => Addons => Extensions and look for any unfamiliar or suspicious looking extensions. When you find any : remove them.

Also look in : 3-bar menu (or 'Tools') => Options => Advanced =>

Network tab => Under : 'Offline Web Content and User Data'

Do the same in Windows' Control Panel => Programs.

However : most malware will be 'hiding' somewhere , so let's run malware scans :

Further information can be found in this article :

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. They all work differently - what one program doesn't pick up, the other might. "

...but as stated before, the malware will most likely re-install any corrupted addons.

I did find and delete 2 addons that I didn't know what they were, that got me closer but still it was opening new tabs in something with Yahoo in the name (I had it cut and pasted here but backed up and went forward and lost it).

Then I installed this addon:

Tab Customization with New Tab Override (WebExtension) by Sören Hentzschel Set the page you see every time you open a new tab.

I now get a blank page and blank address bar but when I do a search using the address bar it continues to use Yahoo when I have it set on Bing. I'm curious what search engines are good and don't track everything you do? I know Google (spyware?) had just about taken over the pc, that is the reason I changed to Bing, and I choose that because it appeared to be recommended by Mozilla.

Well I got it working. I changed my search engine to yahoo, did some searches, then changed it back to Bing and it works. I open a new tab and the cursor is blinking in the empty address bar like it used to and it's ready to type into with no other clicks. Type in whatever and it uses Bing to do a search.