You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

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

Hi, this may also help -Remove “Ads By Name” virus (Easy Removal Guide) by Malware Tips.

tried all the steps of running softwares to get rid od ads by name but it doesnt solve the issue , can someone please help

Did you look carefully through the programs on your PC for anything that looks suspicious as detailed in the above article? It may help to look at the dates when programs were installed, to root out any suspect ones.

yes , very few softwares on my computer now , still the problem persists, nothing seems suspicious now

OK, it's possible that the shortcut icon on the Desktop has been corrupted. So start Firefox from Start Menu > All Programs - or do a search for Mozilla Firefox. If the malware doesn't appear, right click on the Desktop icon > Delete. Now right click on Mozilla Firefox in All Programs > Send to > Desktop (create shortcut). You should now have a clean shortcut icon on your Desktop which you can drag back to the original position.

no that didnt help

• 1 Download Firefox Full Installer For All languages And Systemsv40 {web link}
• 2 Uninstall Firefox from your computer {web link}
  DO NOT remove your profiles.
• 3 After rebooting the computer, run a registry scanner.

Then run the installer.