PHP has encountered an Access Violation at 02892BEB

Hi, i have this error on a win 2003 server with iis6 and php 5.2.5 version 
with ISAPI filter.
I have read that this version is not good and ISAPI is instable so i have 
decided to upgrade to
php 5.3.1 with fastCgi.

How i can remove all reference to older php version on webserver ?
I try to install new php and fastCgi but the webserver run the older version 
and if
i rename the various directory c:\php or php.ini in php-old.ini and put the 
new directory and php.ini file
the webserver don't work with php files.