What I suggest you do is to uninstall/reinstall it again as follows:

• Go to Download Firefox 4.0 and download a fresh installation file to the desktop.

• Just in case Firefox is running, but not responding, hit CTRL+SHIFT+ESC to launch Windows Task Manager, then go to the Processes tab and look for firefox.exe. If you find it, right click it and choose Kill Process.

• Then go to Add/Remove Programs, scroll down to Mozilla Firefox and remove it, choosing to keep your bookmarks, customizations etc., (don't checkmark the box).

• Then reboot and delete the folder called Mozilla Firefox at this location: C:\Program Files\Mozilla Firefox

• Finally run the installation file you downloaded to the desktop earlier.

Thanks for your reply.

I found I wasn't able to delete the file from Ad/Remove programs as that also kept telling me to restart computer.

Eventually I deleted it from Start>All Programs then I was able to download a fresh installation.

While I'm in a question asking mood...are you able to tell me why, sometimes, when I go to a web site, it opens up in a strange, unformated way. If I clear the cache and reload page it comes good.

This seems to happen especially when I go to sites I regularly visit. e.g. newspapers and the weather bureau radar. Also, many videos embedded in the newspapers sites won't play in Firefox but play fine in IE. Is this all part of the same problem?

Cheers,

Ian

Can you give me a few links to newspaper sites which you say won't play videos in Firefox?

As regards the formatting, some sites have ads linked to content. If you block an ad, it also blocks the content. Make sure you have the latest version of Adblock Plus if you use it because I reported just such an issue to them a short while ago and I see now that the problem has been rectified. You can check in the Tools | Add-ons | Extensions menu. Click the icon top right next to the the Search field.