Every so often (and frequently), for no discernible reason, the whole of the top bar of Google and WhatsApp disappears. Sometimes one, sometimes both. The only way to close the program down is to use Task Manager, but I then have to re-boot as reloading Google or WhatsApp just reloads the version without a top bar.
I don't even know where to start looking for a solution to this one!

Windows, Google, and WhatsApp are all up to date versions.