Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

Redstart said

Hi! W8.1 FF34.0 I have installed Google as the default search engine of my FF home window. When I open FF, a spam tag/window appears , with a "Only Search" url ("only search" is the name of the program) For several days, other spam tag/windows can show up with "Fast start" or "Storm Alert" url's. Boxes also show-up providing access to advertising utl's How can I return to my former operation? FF and Google as the default search engine. Thanks Rgds. Redstart

Hi! I have installed and run ADWCleaner V4.106. First impression: FF is in good shape. I'll wait up to Jan 4 to be sure that there is no backdoor open for a malicious SW. Thanks again. Rgds Redstart

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

If you suspect any program or add-on is causing a problem, disable it for a time to see if the issue continues.

Hi!

By removing AdwCleaner; I have removed tap spammed Windows in FF. That's a progress! Bu I notice that sometimes (not always, but most times) , I receive adverisement messages on my FF home window: very nice presentation of these ad's . In my opinion, those ad's are not sent by malicious spamming programs. But are sent by Google itself! (there is no better place to display an ad and to sell it more expensive!). How can I get rid of those ads? I think that the home page of FF should remain without ads. Attached a sceenshot of the FF homepage

Hi FredMcD!

I hope you have received properly the screenshot of my FF homepage.

I will run all the programs you have recommended. But I will run them ony one per day, to make sure which program is providing an additional benefit. Presently, AdwCleaner: postive result Microsoft DecurityScanner: no more available TDSSKiller: I have not yet succeeded to install it

I'll keep you informed. Thanks for your support. Rgds Redstart

I see the picture. Is that the about:newtab page?

In the address bar, type about:home<enter> What do you see?

Hi FredMcD!

Thanks for your support. I think we are over (or very close to the end).

I do not succeed to type exactly what you want (my FF understands French; and do not understand English); but I have done more or less what you are expecting. 1. I launch FF: the home page appears (named "home page" -in French "page de démarrage" -) . 100% perfect. That's the old FF home page I have known for years.

2. If I click over the X of the tab's name, I obtain a new tab (named "new tab" -in French "nouvel onglet" -). The content of the tab is exactly what I have copied in the scrennshot sent to you. That's a new display for me. Are those 8 ad's prepared by Google? Are they prepared by FF? This morning, I thought they were prepared by Google; now I think they are prepared by FF.

3. I type a web address in the address field of the address bar: FF proceeds to the required location I click over the "search sign" in the "google field" of the address bar: the "home tab" is displayed

In my opinion, everything is perfect. Thanks for your support.

I will keep up executing the programs you recommended and come back to you: ---> Microsoft Seurity Scanner is no more available ---> AdwCleaner has detected 2 incidents ---> Malware Bytes'anti malware has detecte 15 additionnal incidents I could not run TDSSkller. I have quesionned our Kaspersky friends. If they answer on Monday I will proceed with TDSSkiller On Saturday and Sunday, I will proceed with Hitmann Pro and ESET Online Scanner

Thanks for your support. Again.

Have a very successfull new year!

Rgds Joel

I wish I understood French. And Polish. and Greek, German, Italian . . . . . .

The about:home (page de démarrage) is a page created by Mozilla. It changes now and then. The best part about this page is the selection of buttons on the bottom of the page. Unfortunately, Mozilla has been making pages that many are objecting to. Even to the point of switching to another page or even an add-on home page.

The about:newtab (nouvel onglet) page will display the web sites that the user visits most. You can, if you want, pin any of the pages so that that page is always displayed.

Here is more information;

Type about:config<Enter> in the address bar. If a warning screen comes up, press the Be Careful button. This is where Firefox finds information it needs to run. At the top of the screen is a search bar. Type browser.newtab.url This tells Firefox what to show when a new tab is opened. If you want, right click and select Modify. You can change the setting to;

about:home (Firefox default home page), about:newtab (shows the sites most visited), about:blank (a blank page),

or you can enter any web page or about: page you want.

The same instructions are used for the new window setting, listed as browser.startup.homepage.

Hi Fred ! Thanks. Your information were interesting and I'll use them. Rgds Joel