I am having the same problem..
As you can see free plugins does not have much support.
Mine gets the following errors when you try to create a new blog within the network with the plugin activated
Warning: fopen(/home/lojas083/public_html/wp-content/plugins/EMPTY) [function.fopen]: failed to open stream: No such file or directory in /home/lojas083/public_html/wp-includes/functions.php on line 3296
Warning: fread(): supplied argument is not a valid stream resource in /home/lojas083/public_html/wp-includes/functions.php on line 3299
Warning: fclose(): supplied argument is not a valid stream resource in /home/lojas083/public_html/wp-includes/functions.php on line 3302
Warning: Cannot modify header information - headers already sent by (output started at /home/lojas083/public_html/wp-includes/functions.php:3296) in /home/lojas083/public_html/wp-includes/pluggable.php on line 881
Some one help?????????