I'm using PHP 4.0.3 on a Linux Suse. Everything works fine, but RANDOM users gets the php script source to their browser instead of the parsed script output.. if they hit reload several times the script will be parsed..I had this problem with 3.0.1[12] too. Apache is 1.3.12 (I tried 1.3.9, same problem), tried PHP as DSO or builtin..same result. 
Compile options:
'./configure' '--enable-track-vars'
'--with-mysql=/usr/local/mysql'
'--with-apache=../apache_1.3.12'                             '--with-imap=/usr/src/imap-4.7a'
'--without-gd' '--disable-debug'

I can count failed requests with a comman like
"grep '<' error_log"
'[Thu Oct 12 06:35:06 2000] [error] [client X.X.X.X] File does not exist: /usr/local/httpd/htdocs/<'

First page contains a link like "/<? print "?ID=1"; ?>" so
when a user has the script source instead of script output in his browser and hit the link the browser will try to load page "/<".
I counted 52 failed requests in one hour (from a total of about 10k requests)

Any help is apreciated.
Thanks