I have been having lots of problems keeping my Movable Type installation running. My host tells me that this is because of comment and trackback spam.

Here's what they said the most recent time this happened:

The 500 error message was caused by the fact that you have reached the limit for maximum number of concurrent processes (20). There were many stale mt-comments.cgi processes running on your account. This was preventing the new processes to run.

The process they pointed to was: /usr/bin/perl -w mt-tb.cgi

Any thoughts on how I can stop this from happening?