I had to install jQuery Update 5.x-2.0 in order to use a great module called Hierarchical Select. Unfortunately the upgrade appears to mess up all of the forms used by user profiles - content block options, media section etc.
It looks like it's CCK Fieldgroup Tabs that is incompatible with the Jquery 2 update: http://drupal.org/node/316005
It looks like it's CCK Fieldgroup Tabs that is incompatible with the Jquery 2 update: http://drupal.org/node/316005