must be a conflict (ajax registration)?

Using joomla 2.5 here: www.gotcharacters.com .
The basic form works, but none of the ajax features (e.g., password strength, etc.) are displaying.

I have several extensions installed, including K2, but I have turned off anything to do with K2 User.  I can't find what might be conflicting.

Any ideas where I should look?

It's a conflict with jQuery which is included by your template.

I constantly repeat: jQuery should not be used on a Joomla site!
Why? Because Joomla already includes Mootools which is basically the same thing.

But developers persist on using jQuery because they are too lazy to develop for Mootools.

Now if they must use jQuery at least implement it correctly in no-conflict mode. If implemented correctly there will be no conflict and Mootools and jQuery plugins can coexist.

But even then there is no point in including 2 heavy JS libraries which do the same but...