Thunderbird keeps disappearing from my taskbar in Windows 10. What will happen initially is that just the icon itself will disappear (replaced by a white "blank" icon), then later even that will disappear, so Thunderbird is gone from the taskbar entirely. This never affects my desktop Thunderbird icon, so right-clicking that and selecting "Pin to taskbar" always works, but only temporarily, till the same thing happens again. This doesn't affect any other icon on my taskbar, only Thunderbird. It's happened 15 times so far (I can tell because, when its taskbar icon is right-clicked, there's a number in parenthesis to the right of the program name for each time that I've pinned it to the taskbar). Can anyone please tell me how to resolve this, so Thunderbird stops disappearing from my taskbar?