for the session:
your session start line should be:
if(!session_id()) session_start();
your host may have an issue with session management. to test use the sessiontest page from the following thread:
showpost.php?p=23826&postcount=2
for the email, are you being redirected to the formresults page?
if so, the email is being sent to the smtp server. It is the smtp server that is not relaying the email for some reason. Contact the host to see if they will look intobthe smtp server error logs to see why the server is not relaying the email.