Sorry to hear about your problem. Please do the following.

• In the location bar, type about:config and hit Enter.
• In the filter at the top, type: keyword.URL
• Double click it and remove whatever's in there. You'll see it revert to "Default" and "String".
• Go to File | Exit
• Restart Firefox, go to the site you want to set as your homepage.
• Go to Tools | Options | General.
• Make sure it says "Show My Homepage" in the first dropdown menu.
• Click the button called "Use Current Pages" to set the homepage to the one you have on the screen.

• Next, go to https://addons.mozilla.org/en-US/firefox/addon/adblock-plus/ and install Adblock Plus.

• Subscribe to "Easylist" (you'll see it during the installation) and then afterwards, go to https://adblockplus.org/en/subscriptions

• Scroll down to the bottom of the list and add Malware Domains to your subscriptions. This one will filter out sites which host malware.

You can also add any of the other subscriptions you want.

applied all of your steps Didn't work! thought it was. clicked on a site thru http://www.google.com/search?q= re directed to take a survey clicked out went back to link right to correct page. again this has never happen with any previous version of Firefox only 4 and with many having similar issue there must be a security issue win FF4 or http://www.google.com/search?q= going to change the search engine to see if that corrects the redirection

In the keyword.URL phase above, add this link instead: http://www.google.com/search?q=

these adds seem to only be in google ran bing all day went back to google went royal caribbean redirect went to bing same url no issues