I am on my wife's MacBook Pro, using Google Chrome, and when on PB there are issues- Flash Player is out of date and can't be updated (though that may be a GC issue), so you have to manually click the "run this time" each time you want to run the bulk uploader. No problems viewing the 'site nor any of my images, though. My wife mentioned needing to update to Apple's most recent OS, but that's not my area of expertise.
How many images (or total amount) do you have stored in your PB account?