Sorry for not getting back to you earlier in your other post. After your last one, we looked up, and found the account you had subscribed from. We were a bit perplexed about the issue though and simply needed more time to investigate.
I just tested on your site, and the very first time I clicked the Login with Facebook button, the button did stay. I clicked it again and it worked as expected. I tried logging out and back in repeatedly and I couldn't get it to happen again, which makes it difficult to test. The first test was with Chrome on a Mac. I also tested with Firefox, after I had already registered, and couldn't recreate it there either.
So, it's hard to tell what happened, but hopefully I can get more information and provide some suggestions:
* If you have any caching enabled on your site, please try to disable it. Specifically, the System - Cache plugin, but also the Global Configuration caching setting as well.
* If you have any 'optimization' plugins for compressing, zipping, or otherwise speeding up your site, disable those.
Test again, and let us know if that makes any difference.
Finally, can you let us know if you're seeing the same behavior only with the first registration, or if it happens on every login for you (unlike us).
Thanks,
Alex