opening / closing mail ………..

here’s a problem that bugs me everytime I encounter it – win98se,win2k, or winxp using ms office 97 prof., outlook 98, or office xp.
when using office and viewing my inbox, I go to open a mail, and the box opens into a small window. I go file and close/exit after I expand the window, then re-open and it still opens into a small window, each time I have to click the middle maximize button to make it open full view. how can this be corrected please & thank you.