Can't add New Events "From Template" after upgrade to 4.6
Other suggestions that might help add clues: 


confirm if you have similar problems with creating Events from templates you created post upgrade. Ie is this problem only relating to templates that existed prior to the upgrade
if any of your clicks result in a pop up box, instead of clicking, right click, open in 'new tab' then continue, that way you should see errors/backtrace (assuming you have this turned on from Admin > System Settings)
compare behaviour between your system and the civicrm demo site.