[Plugin: Constant Contact for WordPress] Error on activation

Not sure why I’m getting this error since I had the plugin working previously on this same site, but now when I activate, I get the following:

“Warning: session_start() [function.session-start]: open(/tmp/sess_flbsod763j3jvnp87k33cgjk07, O_RDWR) failed: Permission denied (13) in /home/impactspeakers/impactspeakers.com/wp-content/plugins/constant-contact-api/config.php on line 61”

I also get this:

“The plugin generated 310 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.”

Any ideas????

http://wordpress.org/extend/plugins/constant-contact-api/