T420S: fullscreen magnifier not working?

[sde]

Anyone,

I have a new T420S (one week old). I really like the machine, but... the fullscreen magnifier (Fn-Spacebar) doesn't seem to do anything. Windows (and the Lenovo software) have already automatically downloaded and installed the latest updates. Can anyone think of something else I should try? Is this a known issue?

Thanks so much,

David