Hi,
Not sure this is the solution to your problem, but what about trying with a more recent version of PHP ?
PHP 5.2.4 is definitly quite old -- so, if it's a bug in PHP's mysqli driver, it might have been corrected since...
Actually, after a quick search, it seems a problem like the one you are witnessing has been introduced between PHP 5.2.3 and PHP 5.2.4 (and was still here in PHP 5.2.5).
See bug #42548 : PROCEDURE xxx can't return a result set in the given context (works in 5.2.3!!)
Are you able to test with something like PHP 5.2.9 or 5.2.10 ?
I know these are not provided by Ubuntu, even in the last Ubuntu stable version :-( You might have to compile from sources :-(
Yet another idea would be to try mith PDO_MySql adapter : maybe it would work with that one ?
It might be possible to change Adapter without causing too much trouble / without taking hours to test ?
As you are working with Zend Framework 1.9, here's another post that might interest you, and might be easier to test : stored procedure error after upgrade to 1.8
An easy solution to try that would be to go back to Zend Framework 1.7 ; would it be possible for you, just to test ?
Anyway... Good luck !
And, if you find the solution, don't forget to indicate what the problem was, and how you solved it ;-)