session_start undefined

Folks, I've been using php w/apache for some time but I've encountered two problems while installing it on a new laptop which I use for development & testing. The first problem is more important to me but I figure the two problems may be related. 1) session_start() is undefined. It is undefined when I access a script via apache 1.3 and when I run scripts by hand. It arises both when I start tikiwiki and my home grown system. 2) If I start apache with mod_php3, httpd gets a SEGV and dumps core. If I comment out the two mod_php3 lines in the httpd.conf apache starts up. Specs: FBSD 4.8. XFree86 4.3.0, Apache/1.3.27, Php 4.3.2RC4. I've reinstalled php and apache several times. Searching the archives hasn't produced anything. Nothing obviously wrong in the config files. Any ideas as to what this is? I assume it's something simple, but I haven't found it yet. thanks dayton