Getting an error after I Installed the plugin

Here's the error I keep getting when I click to look at the item I have listed:
Warning: session_start() [function.session-start]: open(/var/chroot/home/content/70/8951570/tmp/sess_t835qk66qcuao9217erhvk6hd3, O_RDWR) failed: No such file or directory (2) in /home/content/70/8951570/html/wp-content/plugins/marketpress/marketpress.php on line 837

How can I fix this? thanks!