Login fails due to loop on localhost. Any ideas why?
You could find out for sure by adding some logging code in drupal_goto() to backtrace what function fired the redirect. Then inspect why that function fired the redirect and work back from there.

Or, some more "guesswork" approaches -


Check you don't have $base_url set in settings.php.
Clear your cache tables after installing to copy (or don't back up the cache table contents).


drush cc all


Disable modules which might be confused by relocation - securepages, canonical_url, logintoboggan (guessing here). 


drush dis securepages canonical_url logintoboggan


Check your variables table for (and delete) any entries with values like '%http://your.old.domain%'. 


drush vget | grep your.old.domain

drush vdel some_variable_name