There are incompatibility problems between Ask and Firefox which can affect performance in a variety of ways. See http://kb.mozillazine.org/Problematic_extensions

Remove the one you appear to have installed now by clicking the Firefox button, go to Add-ons, then Extensions.

First, make sure that you don't already have that Search Engine installed.
https://support.mozilla.com/en-US/kb/Search%20bar
If you do, does it work? (It may be installed, but corrupted.)
If it doesn't work, try to un-install it from Manage Search Engines at the bottom of the drop-down.

If that doesn't work, remove that search engine from the \searchplugins\ folder in your Profile folder.
http://support.mozilla.com/en-us/kb/Profiles#How_to_find_your_profile

Then try to install it again.

Thank you for the advice.Ask prvided an uninstaller which worked.Have since downloaded Ask UK BUT will not work with FF4.Looks like unfortunely I will hav to go back to IE8. I tried IE9 --hmmm mabe when I get an answer fron Ed Bott Suejames

Ask.com is a search engine which looks for results within its advertiser database. If it doesn't find any, then and only then will you get neutral results. Is this what you really want?

I dont use Ask Jeeves as a search provider but only their dictionary and thesaurus. In SouthAfrica the english used here 9-(spelling etc) is based on the Uk

You could maybe install this add-on: https://addons.mozilla.org/en-us/firefox/addon/british-english-dictionary/ instead.