Reset Firefox
Overview
Over time Firefox can develop problems like slowness, crashing, unwanted toolbars and more. Troubleshooting these issues can be difficult and time consuming. The "Reset Firefox" feature can fix many issues by restoring Firefox to its factory default state while saving your essential information.
Goal
In the event that Firefox becomes unpredictable or is unable to function normally, or if web pages will work in other browsers, but not in Firefox, you may want to try using the steps below to reset Firefox. If you still have problems with an IWU supported website in Firefox after performing these steps, please contact the IWU Support Center at 1-800-621-8667, ext. 2209.
Steps
First Step
At the top of the Firefox window, click the Firefox button, go over to the sub-menu, and select Troubleshooting Information.
Second Step
Click the Reset Firefox... button in the upper right corner of the Troubleshooting Information page. 
Third Step
To continue, click Reset Firefox in the confirmation window that opens.
Fourth Step
Firefox will close and be reset. When it's done, click Finish and Firefox will open.