URGENT HELP! Login Not Working!

I have Membership and a BP theme.

I have just discovered (after initial testing showed all worked) that our Sign Up Here button is going to a Permission Denied page...no wonder we are not getting any course bookings!

I don't know why this would have changed when it worked when tested. Can someone please urgently look at our site (there is access).

Also I tried to log in via iPad and it doesn't work! You enter the user name and password and it just doesn't respond.

What is going on there??? Neither Submit buttton or Click Here to Register works.