In the location bar at the top, type about:config and hit Enter

1. In the filter at the top, type keyword.URL
2. Double click it and replace the current setting with http://www.google.com/search?q= (it has to be entered exactly as you see it written here - but since this is a URL, right click it and choose "Copy Link Location" to copy it to the Windows clipboard, then CTRL+V to paste it)
3. Close Firefox via File | Exit and then restart it again.

To reset it to something else afterwards, see How to set the home page

That didn't change the search engine from the home page search. I attached some pictures. The first is the bar I am searching in (searched "asdf"). The second is the search results. I have searched in this bar on a number of other computers and the result is in Google. For some reason, my search results are in AIM.

I'm still trying to figure where in Firefox 4.0 the pref for the search engine used on the about:homepage is stored or retrieved from, and I don't want to install some garbage just to have to figure out how to fix it and learn that way. What AOL stuff do you installed on that PC? And I'm curious about what was blacked out in you screenshots - if it was a Toolbar extension or just the Bookmarks Toolbar?

Try changing the URL in keyword.URL in about:config to the one mentioned in this blog: http://blogs.techworld.com/war-on-error/2011/01/aol-search-burrows-into-firefox/

The about:home home page uses DOM storage to store the search parameters.

{"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"}

The blacked out sections are just private info and and bookmarks. I don't have any AOL programs on my browser. On my PC, I just have AIM, but it should have no connection to my browser. I have removed anything from my browser that was related to AOL.

I don't know how it worked, but for some reason, it seems to have fixed itself. It wasn't working before, but now it is. Thanks for all your help.