Outlook 2007 - PC - XP Pro

Greetings:

I don't know how I did it, but now whenever I open a new message composition
window the fonts appear huge. When I look at them they are listed as
regular size (i.e. Arial 10 pt.), but somehow the window has become
magnified so the font looks like an Arial 50 pt. How can I reset this?
Your help appreciated.

BG