wordpress blog displaying blank pages [closed]

That’s odd. Perhaps you need to clear your cache or maybe your server takes a while to respond to a changed .htaccess file. (What web host are you using?)

Is there another .htaccess file in the WP folder which might have been modified? Or maybe you’ve made other changes???

By the way, why are you using a 303 redirect instead of a 301? And why not just redirect to http://mysite.com without the index.php and then set the DirectoryIndex directive?