I have a very similar problem.

I bought a used handset last week off ebay that seemed to be working fine - scroll whell, escape key &c. I updated the OS via the desktop manager and turned it off.

Now, coming to set it up after the weekend, none of the keys (power, mute, escape, shortcut, and scroll wheel - but only the 'click' on the scroll wheel; the scroll function works fine) on the side/top of the unit work.

Any ideas?