Can't add any elements to new blank form

I've just installed Gravity Forms and trying to create a simple test form. None of the form elements get added to the new form. Also, I can't save the form, even with no changes.

My environment is the following:
PHP Version 5.2.13
MySQL Version 5.0.92
WordPress Version 3.1.3
Gravity Forms Version 1.5.2.3

I've tested this in Safari, Firefox and Chrome, all on a Mac. I noticed that Firebug in Firefox reported a javascript syntax error about a missing ";" before statement in lines 1 and 2 of tw-sack.js?ver-1.6.1.

Thanks for the pointer David. It turns out both the "Fast Secure Contact Form" and the MailChimp plug-ins conflicted with Gravity Forms. I'm replacing the former with Gravity, but need to use MailChimp, so I need to to figure out next steps here to have both plug-ins working together.