Getting started - only login page working

[eluser]Unknown[/eluser]
Ok, I was able to detect the problem a little better.
The problem is with the controller's JS code. The controller php file has a "js()" function, which returns the javascript code to be used with the page.
It is included in the page like this:

<?php if($js) { ?>[removed][removed]<?php }?>

But fore some reason, the JS code is causing an error. If I comment the entire js() function , the view opens... with none of the JS, of course.
If I leave the method, even with no code at all, like this:

function js()
{
header('Content-Type: text/javascript');
?>

<?php
}

I already get the error and the page is blank.

The weirdest thing is that the login page uses the exact same structure: the controller has a js() function that returns the javascript code. But in the login page, it works.

Any ideas???