Thanks for the info. I had not set that up.
Does it matter what I use for the filter name?
Also, do I right-click <computer name>, under IIS, click on "Edit" in the "Master Properties" section, with "WWW Services" selected, and select the "ISAPI Filters" tab?
Or right click the "default web site", select "properties / ISAPI Filters"?
The first one has some ISAPI filters already listed:
sspifilt, compression, pwsdata, fpexedll.dll. I added "isapifilt" pointing to php4isapi.dll in sapi directory.
The second had nothing listed.
Thanks.