Disallowed Key Characters WTF??!!

For any weird reason, when I send some forms  this message is displayed:

Disallowed Key Characters

WTF? What I changed?? I don't know. I only know one thing: when this message appeared, I had to start debugging the FRAMEWORK, not my code, not your code, just the framework.

I found the problem in file system/core/Input.php, line 727, function _clean_input_keys{}

When I have a POST field containing "-", this doesnt match the preg_match("/^[a-z0-9:_\/-]+$/i", $str), I dont know why because the "-" IS HERE!!! then ...

I run this: var_dump(preg_match("/^[a-z0-9:_\/-]+$/i", '-')); die(); and of course was TRUE.

Conclusion: I don't know WTF is happening (It's like a devil '-' different from '-'), but, if you are seeing "Disallowed Key Characters" message and you have a post field called, for example "login-submit", rename this field to "login_submit" and maybe all the things start working again.