Ive had the same issue and may have a fix for you...it worked for me.
I got the solution from:
http://forum.joomla.org/viewtopic.php?f=428&p=1832038
1) Go to libraries/joomla/html/html/behavior.php located under your Joomla install root (which should probably be your webroot as well) and edit line 108 (unless you've already tweaked the code and changed the line numbers). Here's what you look for.
2) Find$tooltipInit = ' window.addEvent(\'domready\', function(){ var JTooltips = new Tips($$(\''.$selector.'\'), '.$options.'); });';
3) Replace 'domready' with 'load'