Thanks for the Private Message with credentials. I just got in to look around, and don't have much good news. I tried quite a few different things but couldn't deteremine the cause of the problem. Next, I created an instance of the mod_login module (the default Joomla login module). That module also doesn't work on the page you mentioned.
So, I'm not sure what's happening there, but it's not specific to the SCLogin module. It seems any posts aren't working on that page, but I'm not sure why.
I hope that helps you narrow some things down, and sorry I don't have a more specific answer for you.
Thanks,
Alex