Problemas osCommerce

[zika]

hola a tod@s, estoy creando una empresa virtual, y e escogido osCommerce, pues me habian hablado muy bien, lo he instalado y me sale lo siguiente en la parte admin:

Warning: session_start() [function.session-start]: open(/tmp\sess_bc3962a7ea6edf437a8e6bb575710402, O_RDWR) failed: No such file or directory (2) in C:\pcbyte\admin\includes\functions\sessions.php on line 67

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at C:\pcbyte\admin\includes\functions\sessions.php:67 ) in C:\pcbyte\admin\includes\functions\sessions.php on line 67

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at C:\pcbyte\admin\includes\functions\sessions.php:67 ) in C:\pcbyte\admin\includes\functions\sessions.php on line 67

Fatal error: Cannot re-assign $this in C:\pcbyte\admin\includes\classes\upload.php on line 31

Warning: Unknown: open(/tmp\sess_bc3962a7ea6edf437a8e6bb575710402, O_RDWR) failed: No such file or directory (2) in Unknown on line 0

Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0

en la otra (lo que seria la tienda en si) me dice eso mismo mas Advertencia: El directorio para guardar datos de sesión no existe: /tmp. Las sesiones no funcionarán hasta que no se corriga este error.

me estoy volviendo loco, es urgente, si alguien pudiera echarme una mano se lo agradeceria, de antemano, muchasgracias