Weird Javascript error when front page loads

Just checking firebug and have this error appear hundreds of times and also hangs my site every so often...

uncaught exception: [Exception... "Could not convert JavaScript argument arg 0 [nsIDOMViewCSS.getComputedStyle]" nsresult: "0x80570009 (NS_ERROR_XPC_BAD_CONVERT_JS)" location: "JS frame :: http://thatmlmbeat.com/27062006/wp-includes/js/jquery/jquery.js?ver=1.3.2 :: anonymous :: line 12" data: no]

Where would I start with this one?