Ajax checker not working

I have just installed the latest copy of CB on Joomla 1.5. I have set the CB configuration to use the AJAX checker for the username and email. However, it does not check anything. It just goes to the next field when I hit tab without triggering any type of check.

To test it I placed an email I already had and did the same with the username. It did not catch either error until I submitted the page and it posted to the server. It was at that point the page returned with errors.

Is there any other setting I need besides the one in the configuration? I have set this up in the past without error, not sure what I could be doing wrong.

Same problem for me. It just hangs with the little boxes saying " checking... "
It prevents me from administering the entire CB user backend because every edit I do to any part of a user profile it just keeps hanging o checking....
I need to disable email checking onthe backend, despearately!

Thanks