Button created in Access2002 doesn't work in Access2000

I have an app. that I created in Access 2002 (Office XP).
The user I have created this app. for has Access 2000,
when the app. is opened for the first time the Command
Buttons on the menu page do not respond. They appear
depressed when clicked on and appear normally again after
the click is released, but nothing else happens. These
buttons simply open a form, nothing fancy. If I have the
user close the app. and re-open it the buttons work fine.
Until the next time it is closed and reopened. Very
stange. Any Ideas?

Joe