Microsoft Word - Office 2010: The ribbon icons are suddenly very big

When I open Word, it kind of looks like my screen has suddenly been set to a lower resolution, but it hasn't. It's just that all the icons on the ribbons, as well as the status bar & shit are being displayed larger than normal. It's enough to be annoying and enough to make them all pixelated. This occurred suddenly. It is this way in all Office programs, but here is a picture of Word:
 
http://files.myopera.com/gorcq/albums/2574441/Office2010.png.

I have attempted to fix this by restarting the computer, but this had no effect. I then spent some time examining the Word options (where all the pictures also appear slightly too large) in case I had somehow selected the "Show excessively large icons" checkbox — this exists in the latest version of OpenOffice.org, but to the best of my knowledge it does not exist in Word 2010. I also tries running the program in compatibility mode for various other versions of windows, but this just prevented it from having a transparent title bar while not having any effect on the problem.

Does anyone know what this is and how to change it back?

It appears the problem is linked with your Windows Theme. One of the values in menu bar font sizes is too large. The quickest way to overcome the problem is just to reset back to a default theme.