Sounds like something generated by an add-on. Is there anything on that page suggesting the source?

You may want to try disabling ALL nonessential or unrecognized extensions on the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then, if in doubt, disable.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Does that kill the extra tab?

Thank you so much!! It was an Astromenda add-on that I didn't even mean to add on. I think Avast put it there. It was a small problem, but it was really getting to be a pain in the *ss!

That one seems to be going around. In case it has other tentacles, here's what I generally suggest for cleanup:

I suggest starting here:

>> Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Take out as much trash as possible here.

>> Next, in Firefox, open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

(1) In the left column, click Plugins. If you find a plugin that you don't recognize or which doesn't sound essential, try setting it to "Never Activate". (The most essential Plugin is Shockwave Flash. You can use most sites without the others.)

(2) In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

>> Finally, you can supplement your regular security software and "mop up" any remaining issues with the scanning/cleaning tools suggested in this support article: Troubleshoot Firefox issues caused by malware. Those are free and take a long time to run. If they seem to finish quickly and especially if they require a purchase to clean your system, you may have a serious infection. Try the specialized forums listed in the article.

Hopefully not all needed, but just in case.

See also:

• http://malwaretips.com/blogs/astromenda-removal/

You can use the SearchReset extension to reset some preferences to the default values.

• https://addons.mozilla.org/firefox/addon/searchreset/

Note that the SearchReset extension only runs once and then uninstalls automatically, so it won't show on the "Firefox > Add-ons" page (about:addons).

Hello. Thanks everybody for the posts on this topic. I am having the same problem as described by the OP. But, while I do use Avast, I do NOT have the Astromenda Add-on that's been mentioned. I do however have the SB Toolbar installed, and it was recently updated, on 12/29. I suspect this is the culprit, if this problem is in fact not caused by a Firefox update (my tiles were reset on new tabs recently, and I suspect Firefox for this problem).

I am willing to remove the SB Toolbar, but would rather keep it (yes, I admit I am silly) if this annoying "new window = 2 tabs with "new tab" on top" would just go away.

Aside from SB Toolbar removal.....does anyone have any suggestions? I don't see any recently added add-ons/extensions that I do not recognize, aside from the SB Toolbar update.

Update: 5 min after posting this, I disabled the SB Toolbar, and restarted Firefox. No change.

Hi Modoc, if you review the unwanted tab carefully, can you discover any hints as to its origin? For example:

• address bar: does it contain any address?
• page content: does it contain any "about" or "opt-out" type links?
• source code (press Ctrl+u): does it have links to unknown third party websites that could be providing the content or profiting from it?

Hi jscher2000, thanks for the reply!

It's just a "standard" New Tab for mozilla, with no address, and the bookmark tiles in the window.

I've scanned twice with Malwarebytes since my first post, and it found a lot of stuff it didn't like. Even the second scan found 124! Ugh. Anyway, the problem is still the same, and I am starting to think it's a new Firefox feature, and I just have to find a setting in the browser that doesn't show the New Tab instead of the "target" webpage when opening a new window. Does that make any sense?

Update: My third scan with Malwarebytes yielded 0 threats. It also appears the SB Toolbar is gone, and that's ok, if Malwarebytes says so.  :P

Well, I figured it out. It turns out there is a Mozilla add-on (whose name I can't quote exactly because it's no longer in my browser and I can't seem to find an add-on with the exact title) called something like "Mozilla New Tab 4.0".

I opened FF in Safe Mode and my problem went away. I had only 3 add-ons to choose from: Avast, a Garmin one, and the Mozilla one. The only one that made any difference when disabled was the Mozilla New Tab 4.0.

Before getting this far, I had emptied my PC of all Malware (at least according to the Malwarebytes scan), so it doesn't seem Malware is to blame for somehow "messing with" the Mozilla New Tab 4.0 add-on. Who the hell knows.

Do not get confused by an extension that has Mozilla in its name. This is in most cases malware that tries to persuade you that way to get installed. Mozilla only has a few extensions and they usually do not have Mozilla in its name, but Mozilla can show as the publisher and are hosted on the Add-ons website and thus checked.