Hello,

I have exactly the same issue! I'm from Poland, in my case Polish letters are filtered not properly and also Zend_Validate_Alpha is not working for me (because it's using Zend_Filter_Alpha ;-) ).

I've tried to set locale into 'pl_PL' by doing: set_locale(LC_ALL, 'pl_PL'), but this still doesn't work.

Any ideas? I just can't unload mbstring extension because it's compiled into PHP :/