Home page with pipe character opens extra tabs when Firefox starts
Firefox sets multiple home pages when you separate each address with a pipe character (|) or vertical bar. This feature may lead to problems when an individual home page address contains a pipe character.
Here's how to fix it:
Click the menu button
and choose Options.Preferences.
Select the General panel.
In the Home Page text box, replace all pipes (|) with %7C.
Close the about:preferences page. Any changes you've made will automatically be saved.
Tip: If removing the pipe character doesn't solve the problem, add-ons or malware might be causing this behavior. Try refreshing Firefox to remove add-ons without erasing your browsing information and bookmarks.