Why don't Logitech keyboards' media keys work?

I get weird behavior with Windows 8, on several computers (HP and Dell laptops, and a tower PC) with different Logitech keyboards (K800, G15, and G510): right after the Windows installation, everything works fine. But after the first batch of updates, the media keys (sound +/-, backward/forward, play/pause) donn't work anymore.

Note that I've never installed any driver for my Logitech hardware (and everything has always worked fine so far). I performed the test with the tower PC and the K800 keyboard, but it didn't change anything.

Solution found on this Logitech forum's thread: G510, Media Keys and Windows 8

It looks like one of the first updates messes up the HID (Human Interface Device) service activation. In order to fix it, follow these steps:

1. Press Windows+X and select "Computer management".
2. At the left, under "computer management", you find "Services and Applications". Open it and select "Services".
3. Search for a service named Human Interface Device Access (or something VERY similiar).
4. Once found, check the status. If the value is not "Started", start it.
5. To make sure it will be on also in the future, check the Startup Type value. If not "Automatic", right click it, and select properties.
6. Under the tab "General", change the Startup type to Automatic.
7. Apply and close.