I think you might need to disable or remove the 7go Extension as the first step. You can do that here:

orange Firefox button (or Tools menu) > Add-ons > Extensions category

Usually a link will appear above a disabled extension to restart Firefox. Go ahead and click that as needed.

After restarting Firefox, where does 7go still appear -- for example, button on the Navigation Toolbar (address bar), or on your Bookmarks Toolbar, or somewhere else?

Note that your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.

The user.js file is only present if you or other software has created it, so normally it wouldn't be there. you can check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

Rename or delete the prefs.js file and possible numbered prefs-##.js files and a possible user.js file to reset all prefs to the default value.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

7go.com is a very tricky redirect virus. Do not trust the advertisements on the page. Instead, u should remove it as soon as possible. If u lack expertise in fixing that, pls contact an online computer expert 24/7 for help.