I also started experiencing this problem - also with Windows 7 64bit. My laptop is EB series though. Funny thing is that the keyboard actually works outside Windows (in BIOS for example), so apparently this is a software issue. No updates helped - neither from Microsoft, nor from Sony. My guess is Windows Update messing up with hardware, but still I would like some info and, of course, solution to the problem. This post was written with on-screen keyboard.