Although I have submitted code to fix problem where by Apache/IIS GPF under windows when the Ingres module is unloaded I am not 100% certain the problem has been resolved. Until Dec 23rd 2005 I had a reproducable case on my laptop which was stolen from outside a pub in Slough. My replacement machine unfortunately does not reproduce.
If you have a spare few moments and are interested in PHP on Windows with either IIS or Apache please drop me a mail (grantc@php.net).