spamassassin false positives on local users

We've got a Redhat 8.0 box running qmail, vpopmail, and spamassassin (spamd). The employee who originally setup these items covered his tracks well, then left the company in a huff. I understand the principals of the modules, but have had no experience with the details, and my web searches have not turned up much.
My problem is: about a month ago, all of the internal emails (i.e., the ones sent between the users at this site) starting being tagged as "** SPAM **". I've checked all of the configuration files I could find, and none of them has been modified since September 2003, when the modules were initially setup.
Can anyone tell me where to start looking?

Try looking in /etc/mail/spamassassin/local.cf and look for the directive...

rewrite_subject 1

and change that to 0 instead.

Unless you're getting a lot of value out of running spamassassin, I would simply turn it off. It uses a whole lot of CPU cycles and IMO, there are many other more effective ways to control spam.