Check your installed uBlock logger to make sure you are not blocking something that is causing the page not to fully render.

You can check the Web Console (Tools -> Web Developer) for messages about blocked content and about the presence of mixed or unsafe content. *https://developer.mozilla.org/en/Tools/Web_Console Did you make changes to the default font settings in "Options/Preferences"? *Options/Preferences -> General: Fonts & Colors -> Advanced What font is Firefox trying to use if you check this in the builtin Inspector? You can right-click and select "Inspect Element" to open the builtin Inspector with this element selected. You can check the font used for selected text in the <b>Font</b> tab in the right pane of the Inspector (this item might be hidden in the overflow area). *https://developer.mozilla.org/en/Tools/Page_Inspector/How_to/View_fonts