see this part of the error:
output started at /nfs/c05/h03/mnt/76361/domains/hellointeractivedesign.com/html/jobs/OTL/html/healthcareprofessional/registration.php:18
it is reporting the output around line 18 of the /registration.php page.
Send a copy of the registration page so I can look into the other issues you report.