Perhaps when you try to make the connection you should check the return value and use whatever PDO error-checking methods exist to find out what went wrong, instead of blindly going forward assuming you have a database connection when you don't.
As a said before I have dumped the hander and all the params before passing them into the function and the object has been crated. As I said the exact same code works in the same system using a different (compiled) apache and a different (compiled) version of PHP without any problems. It also works in another system using a compiled apache and PHP.
Ditto for any result of ->query()
What you are doing now is akin to turning the key in a car, not listening to see if it started, and asking a mechanic on the phone why the gas pedal doesn't work...
:-)
So I will have to assume that the rpm is not behaving as expected or that there is a bug in that specific version of PHP.
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Thodoris