Hi,
the error message
could not create 'table name'.frm
is a hint that php has mysql support at all because that error message rather comes from the MySQL database. Please check the directory permissions of the MySQL database directory (something like /path/to/mysql/var or /var/lib/mysql). Make sure that the MySQL user has write permissions on that directory.
Regarding the sessions:
Make sure that the session.save_path configuration variable in php.ini points to a valid and writable directory and that the session settings are the same as with the previous PHP installation. Did you replace php.ini with a new one ?
Thomas