PHP4 instabilities on NT4/IIS

I'm running PHP4 (isapi version) and am noticing some instabilities with it. This is the February 28 build (since that was the last build that worked with sessions). Anyhow, I'm running both ASP and PHP pages on this box. It seems that the PHP will die eventually (after 1/2 or less) and then the ASP pages quit working as well. Inetinfo then has to be killed off and the web service restarted. I'm curious if anyone else is running PHP4 on NT/IIS4 as an ISAPI component with any issues or success, particularly with a number of users hitting the server. I'm considering using the CGI version if necessary. What would I give up if I did that (instead of ISAPI)? Or perhaps APACHE on NT? Gerry