After installing plugin Smart Image Gallery site unaccessible

After adding the plugin in a upgraded installation of WP in Multisite configuration I cannot anymore load the site ad appears this error:

Warning: fopen(/htdocs/public/www/wp01/wp-content/plugins/photoshow//wpeditor.php): failed to open stream: No such file or directory in /htdocs/public/www/wp01/wp-includes/functions.php on line 3666 Warning: fread() expects parameter 1 to be resource, boolean given in /htdocs/public/www/wp01/wp-includes/functions.php on line 3669 Warning: fclose() expects parameter 1 to be resource, boolean given in /htdocs/public/www/wp01/wp-includes/functions.php on line 3672 Warning: require_once(/htdocs/public/www/wp01/wp-content/plugins/photoshow/classes/WPEditor.php): failed to open stream: No such file or directory in /htdocs/public/www/wp01/wp-content/plugins/wp-editor/wpeditor.php on line 71 Fatal error: require_once(): Failed opening required ‘/htdocs/public/www/wp01/wp-content/plugins/photoshow/classes/WPEditor.php’ (include_path=’.:/usr/share/php:/usr/share/pear’) in /htdocs/public/www/wp01/wp-content/plugins/wp-editor/wpeditor.php on line 71

The site is: “http://www.artefvg.org/wp01/”
Where Fopen() gets the var that appears to be wrong?
Any solution?
Thanks

https://wordpress.org/plugins/photoshow/