I also received this error after submitting registration form (i see a blank page)and when i check my email,
there isn't the confirm code.

Cannot redeclare class compa in /home/examoff/public_html/examofficers/administrator/components/com_jnewsletter/compa.php on line 4

when i checked codes, there are two compa class. one is in acajoom and other is in jnewsletter.

also my memory_limit is 256M.it's not because lack of memory.

please help us to solve this problem asap.