Mailscanner max'd out CPU/memory and not processing mail

[Tom Rogers]

I've been using Mailscanner for a few years now with no problems.  Two weeks
ago, I started to have a problem.

When I run Mailscanner, it maxes out my CPU and the amount of memory it uses
keeps climbing and climbing, until it eats all available memory and basically
freezes the system up.  Mail is not processed from the Postfix hold queue.

The system is basically used only by myself, for LAN file storage and email. 
It's a P2 333mhz, with 512mb of RAM, which has been just fine for my needs.

Using Postfix for mail delivery; the OS is Ubuntu 6.04.

I've disabled Spamassassin, but still have the same problem.

Running Mailscanner in debug, I get the following:

root at fatman:/home/tom# /etc/init.d/mailscanner start
In Debugging mode, not forking...


>From the /var/log/mail.info (nothing in the mail.err or mail.warn):

Mar  6 16:10:48 fatman MailScanner[7063]: MailScanner E-Mail Virus Scanner
version 4.57.6 starting... 
Mar  6 16:10:49 fatman MailScanner[7063]: Read 759 hostnames from the phishing
whitelist 
Mar  6 16:10:49 fatman MailScanner[7063]: Config: calling custom init function
SQLBlacklist 
Mar  6 16:10:49 fatman MailScanner[7063]: Starting up SQL Blacklist 
Mar  6 16:10:50 fatman MailScanner[7063]: Read 0 blacklist entries 
Mar  6 16:10:50 fatman MailScanner[7063]: Config: calling custom init function
MailWatchLogging 
Mar  6 16:10:50 fatman MailScanner[7063]: Started SQL Logging child 
Mar  6 16:10:50 fatman MailScanner[7063]: Config: calling custom init function
SQLWhitelist 
Mar  6 16:10:50 fatman MailScanner[7063]: Starting up SQL Whitelist 
Mar  6 16:10:50 fatman MailScanner[7063]: Read 18 whitelist entries 
Mar  6 16:10:50 fatman MailScanner[7063]: Using locktype = flock 

After about 20 minutes, the CPU is still at around 98-99% and using 450+MB of
RAM (on my installation, Mailscanner uses 60-70MB of RAM per instance).

I've tried removing/purging/reinstalling Mailscanner, but keep coming up with
the same results.