I had found an infection at a site with single site wordpress installed and after I removed the infected files the site crashed due to the OSE firewall plguin. These are the errors it was causing:
Notice: Undefined index: osefirewall_sfspam in ,,,/wp-content/plugins/ose-firewall/library/osewpfunctions.php on line 45
Notice: Undefined index: sfs_confidence in .../wp-content/plugins/ose-firewall/library/osewpfunctions.php on line 46
I had to deactivate the plguin to run the site.