Are you running Firefox in Windows XP Compatibility mode? If you are, please disable that, and then install Firefox 62. You'll need to download it from www.getfirefox.com

One is FF update advisor one is Windows update two different things. So where and what FF version did you download from? Firefox 52.9 is out of date it's FF62 now.

https://ftp.mozilla.org/pub/firefox/releases/62.0/

Hi ma-jnk, just in case you didn't already discover how to check whether your Firefox is running in Compatibility mode:

Find the icon you use the start Firefox, and either:

• Right-click a desktop shortcut, then click Properties
• Right-click a Firefox icon pinned to the Taskbar then right-click Mozilla Firefox, then click Properties

You should clear all the boxes on the Compatibility tab for best results (giant screenshot below).

Any difference the next time you start Firefox?

Yes, thank you so much! I would never have thought about it, since there was no reason to run FF in compatibility mode. After disabling it, the updater worked, so there was no need to download/install the newest version.

jscher2000 said

Hi ma-jnk, just in case you didn't already discover how to check whether your Firefox is running in Compatibility mode: You should clear all the boxes on the Compatibility tab for best results (giant screenshot below). Any difference the next time you start Firefox?