mod_perl "bug". On occasion, the regex engine doesn't work as it is supposed to and punctuation doesn't get inserted into a date. Similar bug also sometimes causes nodes to be dated as "on never".

We also sometimes get "bizarre copy of ..." errors in the log, the XML feeds used to randomly not encode (or was it double-encode?) (we switched away from XML::Writer and that problem disappeared).

I've seen these things enough times to strongly suspect that they happen when one of the httpd processes overwrites some part of memory it shouldn't have and so, until that process gets recycled, a certain percentage of hits will be serviced by a not-quite-as-sane-as-usual instance of the Perl interpretter.

One day we'll try a new build of mod_perl. Based on my previous experience, the first such try will likely be less stable than what we've got now.