asp classic - Footer doesn't move down when the left side menu is large -

i had redone css allow footer stay @ bottom of our product page seems if left-hand side contains more information body does, footer cuts left off, instead of moving down allow left-menu shown. i've tried number of different solutions , think may have page being dynamically generated (asp classic) don't have option of specifying height. insight should either do, or appreciated.

thanks.

the problem have because left menu position: relative;, there other problems prevent simple solution page.

my advice check other 3 column css layouts, the perfect 3 column liquid layout