PHP Love/Hate - Inheritance Depth

Just made the discovery that class inheritance has its limits in PHP. It took several days of pain to discover this, due to the fact that my hosting server (5.1.6) does not run exactly the same version as my dev environment (5.2.5), and the particular transaction I was testing is initiated by PayPal.
Lesson learned:

• Single inheritance is ok
• > 1 inheritance depth fails in some versions

I guess I'm spoiled my the elegance of Java and Ruby, expect industrial strength engines. And I have to admit I am no virtuoso in my command of PHP.
Hopefully eclipse Galileo's PDT 2.1 (PHP Development Toolkit) might ease my dev pain.