wizard form and checkboxes that won't turn off

[Janice]

Could somebody please refer me to a solution to this?  
 
I have a form bean (session-scoped) that is displayed over 3 pages.  There
are "back" and "next" buttons.  Once a checkbox is selected and the user has
moved to another page, it can't be cleared again.  I have read that this is
because the checkbox item is now in the session and simply unchecking it
does not remove it from the session.  What I haven't found is a solution or
workaround.
 
I am using struts 1.1.
 
Thanks very much in advance,
J