apache 2.2.21 - back to 2.2.20 ?

[Sergio Tam]

2011/9/20 n dhert <ndhertbsd at gmail.com>:
> Monday I did a portupgrade
> apache-2.2.20                       <   needs updating (index has 2.2.21)
> There was no problem during the update (and nothing special mentionned in
> /usr/ports/UPDATING)
> Today Tuesday afternoon I did a
> # apachectl graceful
> Since them, several webpages give problems
> this error comes up:
> warning: preg_match() [function.preg-match]: Compilation failed: internal
> error: previously-checked referenced subpattern not found at offset 389 in
> /usr/local/www/apache22/data/drupal-6.22/includes/database.inc on line 347.
>

Your drupal its old versión, i think work with php 4 and now you have php5

Try to upgrade drupal.