White Screen Firefox

I too had a completely white screen when starting Firefox 39.0. No menu, no x to close the window, nothing at all. It appeared Firefox was somehow starting in full screen mode, and I have a blank screen as my home screen

Edit: FF version added

Dick99999 said:

I too had a completely white screen when starting firefox. No menu, no x to close the window, nothing at all. It appeared Firefox was somehow starting in full screen mode, and I have a blank screen as my home screen

Hi:

This is actually a 4-year old topic based on a now-long-extinct version of Firefox.
So it's unlikely anything suggested back then will be of much use now, with the current version.

The first step would be to proceed stepwise through the STANDARD DIAGNOSTIC.

If Mozilla safe mode (NOT Windows safe mode) & other steps suggested HERE (such as disabling hardware acceleration, as suggested) don't resolve the issue, then a more drastic (but helpful) step is the creation of new, plain, "vanilla" profile (with no installed extensions, no changes to preferences, etc.).
(You don't lose the "old" profile, especially if you back it up first.)
If that fixes the problem, then bookmarks can be imported from the old profile, and (one-by-one) extensions can be installed and preferences "tweaked".

You might also want to check your plug-ins, such as Flash Player, and consider doing a clean upgrade to the current version...

Let us know how it goes,