I'm using apache-2.0.40 + php-4.2.3 now, it works very well, just like apache-2.0.36 + php-4.2.1.
But before php-4.2.3, apache-2.0.40 cannot work with php-4.2.1 and php-4.2.2 because some APIs were changed in apache-2.0.40, I believe in php-4.2.3 some adjustments had done.