What might cause runaway httpd?

[Michael Smith <mj...@cursci.co.uk>]

I got in to work just now to find the following processes have been
eating up CPU time most of the night:

  PID USERNAME PRI NICE  SIZE   RES STATE   TIME   WCPU    CPU COMMAND
28285 web       27    0 2220K  900K run   212:40 35.74% 35.74% httpd
25478 web       26    0 2220K  888K run   249:02 33.70% 33.70% httpd

(I am running Solaris 2.5 and apache 1.1.1 with various optional
modules).  What might cause this?  Is this simply something that happens
with the server every now and then, or is it something caused by bad
CGIing?

Any ideas greatly appreciated; or I guess I'll have to try and set up
some cron job that looks for nasties and kills 'em.

Mike