Spam training "spammng" process occupies all memory on the Plesk server and as a result Spam Filter Training tab is depicted incorrectly.
SOLUTION:
Try attached file for all OSes. Replace file into /usr/lib/perl5/site_perl/5.8.5/Mail/SpamAssassin/
File is at original post:
http://forum.parallels.com/showpost.php ... stcount=68