Once in a while under Apache 2.0.55 or 2.2.2, I would get a crash with a line like the following in the log:
[7508] EACCELERATOR: PHP crashed on opline 48 of preg_replace() at G:\DomZeus\sitebuddycom\wwwroot\modules\search.module:354

This mostly likely an eAccelerator bug (not 100% sure).
Meanwhile here is a solution to try to avoid it. Since in my case the error happens regularly (once a day?) with the file search.module, I decided to tell eAccelerator to stop trying to cache that file with:

eaccelerator.filter="!*earch.module"