cannot select profile for online event registration after upgrading civi on Joomla
I also had a similar issue where I could not select Profiles in Civi.  I am on a Wordpress site.  I found that Civi had a conflict with my theme (it was not a problem if I changed back to the default theme).  In my theme's functions.php file it had the following include which was causing the problem:

include_once('mkdinc/plugins/visual-composer.php');

I changed it to this:

if(isset($_GET['page']) &amp;&amp; $_GET['page'] == 'CiviCRM')
 ;//dont include it breaks civi
else
 include_once('mkdinc/plugins/visual-composer.php');

and the profiles were useable again.  Hope that helps.