After I finished the 2011 to 2013 upgrade in my test environment, I attempted to try out the new 2013 included forms. Unfortunately, every one I've tried has errored out with a "Error on page" then a "A problem has occurred, send to MS" popup after clicking away from that entity. If I go into customizations - any of the entities with new forms - disable that form so just the old "information" (pre-2013 form) is active, the entity loads.
Any idea how every one of the new forms could have issues? I have not attempted any kind of a form merge between the new 2013 form and my pre-existing 2011 form.