Random segfaults

Ever since I dist-upgraded the Debian install on one of my Linodes yesterday, I've been experienced random segfaults reported by cron (via e-mail), like this one:

/bin/sh: line 1: 11868 Segmentation fault      /usr/bin/php /web/monitor/inc/update_spider.php 2> /dev/null

This particular PHP script is set up to run once a minute, and it's part of a server monitoring solution I have created. This particular script just checks the database whether a particular spider bot has visited its designated ping URL and updates the spider's UP/DOWN status based on that. So basically, the segmentation faults doesn't occur every time the script runs, just at random times. It has only happened once over the last 5 hours, but in the 12 hours before that, it has happened about 10-15 times (I didn't count before deleting those e-mails).

I did experience connection problems on my end (short ISP outage) while I attempted the dist-upgrade the first time around (I performed it via a regular ssh connection rather than via LISH), but this upgrade seemed to finish off nicely (from the start, except for the packages that had already been downloaded) after I was back online. I have no idea whether this might have been a contributing factor to this segfault issue or not, though.

Any ideas what might solve these problems?