You can look at Adblock Plus.

• Adblock Plus: https://addons.mozilla.org/firefox/addon/adblock-plus/

You need to subscribe to a Filter list (e.g. the EasyList).

• http://adblockplus.org/en/subscriptions
• http://adblockplus.org/en/getting_started

Thanks to the reply to my problem, but I don't want to install another add-on that might make matters even worse. I have removed an add-on called Yonto Layers and that seems to have removed the problem. By the way I don't remember even installing this add-on, I wonder if these things are being installed surreptitiously!

Steve

To prevent add-ons from being installed without your knowledge, follow these steps:

-> Tap ALT key or press F10 to show the Menu Bar

-> go to Help Menu -> select "Restart with Add-ons Disabled"

Firefox will close then it will open up with just basic Firefox. Now do this:

-> go to View Menu -> Toolbars -> unselect All Unwanted toolbars

-> go to Tools Menu -> Options -> General -> place Checkmark on "Show the Downloads window when downloading a file" -> select Radio Button option2 "Always ask me where to save files"

-> go to Tools Menu -> Options -> Content -> place Checkmarks on:

1) Block Pop-up windows 2) Load images automatically 3) Enable JavaScript

-> go to Tools Menu -> Options -> Security -> place Checkmarks on:

1) Warn me when sites try to install add-ons 2) Block reported attack sites 3) Block reported web forgeries

-> Click OK on Options window

-> click the Favicon (small drop down menu icon) on Firefox SearchBar (its position is on the Right side of the Address Bar) -> click "Manage Search Engines" -> select all Unwanted Search Engines and click Remove -> click OK

-> go to Tools Menu -> Add-ons -> Extensions section -> REMOVE All Unwanted/Suspicious Extensions (Add-ons) -> Restart Firefox

You can enable your Known & Trustworthy Add-ons later. Check and tell if its working.