I wasn't too sure how to word the title as its a rather obscure issue.
Essentially if you go to http://www.discovertheplanet.net click on one of the 3 boxes and if you are on firefox you will see the issue. If you view on IE or Chrome the menu on the left hand side is in the correct position, however on Firefox it starts way down the page.
I have viewed the console and there were a few CSS errors referring to the bootstrap.css. I have been on the Bootstrap website for known issues with firefox but there was nothing relevant.
My HTML for the main are where the menu is:
<!-- Main Body Area -->
echo "<div style='width: 100%; display: table;'>";
while( $noteName = sqlsrv_fetch_array( $resultNotes, SQLSRV_FETCH_ASSOC))
echo "<div class='hvr-bounce-to-right1 hover-cursor' style='width: 100%; border-right: 5px solid #00AA88; height: 50px;'>" . $noteName['NoteName'] . "</div>";
<!-- End Main Body Area -->
the .main-container-notes height is causing this try removing it