After the instalation and activation of the Directory

Hello,
After the instalation and activation of the Directory plugin I get a warning message :
Warning: session_start() [function.session-start]: open(/tmp/sess_cfacb8aabb7a21e0a7a23f411a7d2161, O_RDWR) failed: Permission denied (13) in /home/lapsiho/public_html/wp-content/plugins/directory/core/core.php on line 1276

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/lapsiho/public_html/wp-content/plugins/directory/core/core.php:1276) in /home/lapsiho/public_html/wp-content/plugins/directory/core/core.php on line 1276

What sould I do ?
I have only this two plugins WPMU DEV Dashboard and Directory .