When you start Firefox, is it set to restore your previous session windows and tabs? If so, that script might be linked into one of those pages. If not, it could be associated with your home page or one of your add-ons.

In case one of your extensions is involved, could you test the page in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference?

After a closer review:

(1) Try disabling the Conduit plugin, as Conduit add-ons seem to be associated with the new tab button not working (e.g., Community Toolbar extensions). Here's how:

Open the Add-ons page using either:

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

In the left column, click Plugins. Look for the Conduit plugin and change it from "Always Activate" or "Ask to Activate" to "Never Activate". You may need to create a new window (Ctrl+n) or exit and restart Firefox in order for this to take effect.

(2) Try removing the "WebSite Recommendation" extension

When I search this, it seems to be associated with ads.

On the Add-ons page, in the left column, click Extensions. Then scan down the list for this one and try to Remove it.

If there is no Remove button, you usually need to remove it through the Windows Control Panel, Uninstall a Program. Clicking the "Installed on" column heading will group items by date, which makes it easier to spot undisclosed bundle items that snuck in with some free software.