Not that it's much consolation, but I'm having the same problem here. I've posted on here a while back and not got much help apart from the obvious check your browser privacy settings... which of course is the first thing you do. Trouble is, my script works live, but not local, which is annoying as I can't test it!
I upgraded to XAMPP from an old version of PHP Triad (Apache 1.3.23). I've checked my php.ini and httpd.conf but no clues.
Will let you know if I get it solved.