It sounds like you have installed a persona (light weight theme). For details of how to switch themes and remove personas see https://support.mozilla.com/kb/Using+themes+with+Firefox

Thanks for helping me but there does not appear to be an uninstall button in Firefox 4. I'm still stuck with the picture I'm sorry to say. But thanks anyway, I'll just have to put up with it but with 78 year old sight it's not easy.

Try the following, it will switch to the default theme. First open the add-ons manager to do this:

1. If you have the orange Firefox button, click it then click the "Add-ons" entry
2. If you have the menus, click the Tools menu then click the "Add-ons entry

Now to switch to the default theme

1. In the add-ons manager click on the work "Appearance in the left hand column
2. You will then see a list of installed themes and personas, click on the one called Default to highlight that line, then click on the Enable button on the right hand side, this will switch to the default theme.

Thank you very much my friend for helping out an old geezer. I can see what's going on at last! Kind regards, John