Hi,
1 hour ago it was still ok.

But now it shows me the loading screen, then does nothing. Almost nothing. It adds a string in the URL bar like this:
mywebsite.com/index.php?fblogin=1
mywebsite.com/index.php?code=4/p247O-mt0aCCe_-ptvQQiOLPvW4Hv6mFbxotD_Guobg#

I am very sure I didn't install any other extension to my system, but now I can no longer login by facebook or google, nor can I register new user. Very frustrated, Please Help!!!!!!

Best regards

Hi,
you should know better than me what you did :O
I can only trying to guess!!!
I suspect that you changed the assignments of the IFBL module, from all pages to selected pages and now it's skipped and doesn't take effect.
Rule of thumb: don't touch what is working!

Best regards

John:

I didn't change IFBL module, it was selected pages before.
For your words, I tried to changed the setting to all pages, still not work.
Not this guess. Still need your help~

I've no other ideas, only thing if you got URLs like:
mywebsite.com/index.php?fblogin=1
mywebsite.com/index.php?code=4/p247O-mt0aCCe_-ptvQQiOLPvW4Hv6mFbxotD_Guobg#
it means that the login module takes no effect or is not executed.
Try to restore an earlier version of the website.