BuddyPress.org

I´m running a BP+MU intallation, so users can create blogs when signup, the problem in that everytime I create a new account and blog, I receive the e-mail to activate my account and I click on the link, I´m redirected to the confirmation page that says the activation was sucessfull.

But on the top of the site appears the following errors:

Warning: sprintf() [function.sprintf]: Too few arguments in /home/derekmelo/www/wp-includes/ms-functions.php on line 1065

Warning: fopen(/home/derekmelo/www/wp-content/plugins/EMPTY) [function.fopen]: failed to open stream: No such file or directory in /home/derekmelo/www/wp-includes/functions.php on line 3493

Warning: fread(): supplied argument is not a valid stream resource in /home/derekmelo/www/wp-includes/functions.php on line 3496

Warning: fclose(): supplied argument is not a valid stream resource in /home/derekmelo/www/wp-includes/functions.php on line 3499

But the new blog and the new account is created normally.

I´ve already re-installed everything with no plugin activated, just buddypress, set up the multisite, try to create a new site, and again, the same thing.

Can you help me guys?

Thanks