Yes, you should be able to use the 2. Can you give a lot more info on what you enabled though? Joomla Global Config caching, System - Cache, some 3rd party extension, etc? If it was the System - Cache plugin, please make sure it's ordered last (highest number).
Also, when it loops, do you get an error, or other message? What page does the user end up on? Is this with new registrations or returning users?
Beyond that, with more information, we should be able to help get you going.
Thanks,
Alex
Login-loops
