Why is it that search box in the centre of the homepage does not work, though it works fine on a secondary user page on the same computer?

Question

Recently updated to latest version of Firefox. On my home page of Mozilla, there is the Firefox "ball" icon and underneath, two long boxes. The first has the word "search" next to it and the second is emty. I can type into the upper box, but when I click search, nothing happens.
My wife is a secondary user and has her own logon. Her mozilla homepage is slightly different in that the lower of the two boxes on the homepage conatins "Thank you for choosing Firefox..." and when a question is typed into the search box, clicking on search works fine.

Answer 1

Thanks the-edmeister that put me on the right track. I was having the same problem and in the console was an error: -
Error: gSearchEngine is null
Source File: chrome://browser/content/aboutHome.js
This lead me to a thread that discusses this: https://bugzilla.mozilla.org/show_bug.cgi?format=multiple&id=637639
The solution proposed, to go to the about:home page and enter the following into the URL bar, worked for me.
javascript:{localStorage["search-engine"]="{\"name\":\"Google\",\"searchUrl\":\"http://www.google.com/search?q=_searchTerms_&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a\"}";void(0);}
I also had DOM storage enabled during upgrade and indeed all of the time (unless something is messing about with it in the background).
A VERY irritating bug because while you can easily set your home page elsewhere you still feel like there is something broken in the background and actually there is as there is no explanation as to why the problem occurred with DOM stored on.