I click the "Tools" tab, then click the "Add-ons" tab. If I then click anywhere on the "Add-ons" dialog box, the dialog box immediately closes. I can't install plug-ins or add-ons. However, this happens only with my account. Other users have no such problem. I have also tried going to the "Add-ons" dialogue box through "Tools" then "Options." I still cannot get into the "Add-ons" tab; the dialog box closes. I have tried using the keyboard instead of the mouse; same problem. == This happened == Every time Firefox opened == I am unsure what caused it. I have tried re-installing firefox.