error message when I extended a site

I went to extend a new blog today and received this error message

Warning: fopen(/home/influncr/public_html/wp-content/plugins/automessage/automessage.php) [function.fopen]: failed to open stream: No such file or directory in /home/influncr/public_html/wp-includes/functions.php on line 4339

Warning: fread(): supplied argument is not a valid stream resource in /home/influncr/public_html/wp-includes/functions.php on line 4342

Warning: fclose(): supplied argument is not a valid stream resource in /home/influncr/public_html/wp-includes/functions.php on line 4345

Please help as now anything I do on the blog seems to disappear an hour later!