I just tried the Facebook login button, and the popup was a blank white window. Is that what you're seeing?
If so, please go to [
developers.facebook.com/apps]the Facebook Developer Area[/url], click into your app, go to "Status & Review" and then ensure that your app is "Online and available for everyone".
If that doesn't help, or your app is already online, please try disabling the caching and Javascript minimization occurring on your site. Test that way, and if it doesn't work, let us know. We'll gladly test further to see what may be wrong.
Thanks,
Alex