rewrite, php and seg faults

Hi, and thanks in advance.
I run a couple of sites that use php (php-nuke to nbe precise) and have rewrite rules to shorten the urls for search engines etc in the fashion of modules.php?name=News&file=article&sid=1 returns article-1.html.
My problem has been, that ever since putting these rules in (both .htaccess, header.php and footer.php have parts of required code within), I have been getting the following faults in the error logs:
child pid xxxxxx exit signal Segmentation fault (11)
It wouldnt be too bad, if it was just an error, but it ends up slowing the server to a crawl, and at times even stopping it altogether, with manual reboots needed at times.

Can anybody give a suggestion as to what may be the cause, as I have had this in place for about 8 months, and the search engines have links to most of the shortened urls now (literally thousands of them)

Thanks again in advance.

Mick