jQuery floatHeader does not line up with cells on Firefox 3

[jsherk]

Using Firefox v3.6.13 and the jquery floatHeader, when you have a very wide table with lots of columns and you start to scroll down the page, once the floating header appears, the header over each column gets out of alignment with the table cells in the body as much as 50%. It happens in Chrome as well, but only by a couple of pixels so it is still tolerable and usable on Chrome. But in Firefox it is way off!

Could it be something to do with the fact that my first column is not-sortable (not from the database)? Note the first column in the columns array belaow has a space as the title because it will contain an edit button and a view button but no text from database.

Here is how I set it up in my model query.php:

        $pagination = $this->factory('pagination');
        $pagination->columns = array(
            ' ' => '',
            '' => 'id',
            _('ID') => 'unique_id',
            _('Date') => 'date',
            _('Location') => 'location_id',
            _('State') => 'state_province_id',
            _('Country') => 'country_id',
            _('Currency') => 'currency_id',
            _('Cash DEP') => 'cash',
            _('Other DEP') => 'other',
            _('Other ND') => 'other_no',
            _('Foreign Cash DEP') => 'foreign_cash',
            _('Foreign Other DEP') => 'foreign_other',
            _('Foreign Other ND') => 'foreign_other_no');

        $pagination->limitCount = 50;
        $get_results = $pagination->query($this->sql);
        $RESULTS['th'] = $pagination->th();
        $RESULTS['search'] = $pagination->searchForm();
        $RESULTS['nav'] = $pagination->navPages();