If have not updated to FF ver 54 please do so. Am sure this is not a FF issue and is a MS Win 10 issue. Do you use Logitech software for your mouse ? In Device Manager please check that also not running MS Mouse stuff. Can choose to uninstall Logitech and let MS handle your mouse I would think as I do not use Logitech's keyboard software. Logitech also download mouse software when my mouse is MS. You might once get device manager settled out and decide what software is what is to turn off getting hardware updates for your cpu try this https://www.howtogeek.com/302595/how-to-stop-windows-10-from-automatically-updating-hardware-drivers/ Am sure you have a Microsoft or Logitech issue. So Device Manager and pick and uninstall and maybe have uninstall all from there and reboot and will reinstall software.

Hello,

You could try to use Cut, Copy, Paste located in Firefox's hamburger menu:

• Click the menu button

How do you do the Copy/Paste?

You write about programmable mouse buttons. What actions are these buttons set to?

You can try to mouse buttons and actions to the default in the Windows Control Panel Mouse settings to see if that has effect.