[PHP] Failed to write session data (files)?

When I try to use sessions without cookies, I get the following error. Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0 What does that mean? Of course, the session data isn't saved when this happens. The

[PHP] Failed to write session data (files)

When using PHP 4 as a CGI module I get the following error trying to use sessions: Warning: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0 What does this error mean? This only occurs if cookies are