[jQuery] AJaX Error

[jQuery] AJaX Error


I don't think this is jQuery specific, but I'm using jQuery and this
community is helpful as hell, so I thought I'd post to see whether
anyone had any thoughts. I'm making an AJaX call to a PHP page that
returns a lot of data in JSON format.
1. The PHP page is doing a lot of work and could take several minutes
(or more) to return the data.
2. The Apache request timeout is unlimited.
3. When the error is returned, the exception object's message
property reads: "syntax error" with no description.
4. When returning less data (i.e. 3 days rather than 7), the request
is returned just fine.
5. Firebug indicates that the request never completes. The
"Response" tab still says "Loading..." even after the call has errored
and quit.
The code:
$.ajax ({
    type: 'POST',
    url: '/reports/_report.php',
    dataType: 'json',
    data: filter,
    global: false,
    timeout: 900000, // 15 minutes
    success: displayReport,
    error: function ( request, errtype, e ) {
        alert ( 'An error occurred while loading this report. ' + e.message
+ '(' + e.description + ')' );
        $( '#out-' + report ).empty().append ( '<strong><em>Error</em></strong>' );
    },
    complete: function() {
        $(indicator).css ( 'visibility', 'hidden' );
        $(src).css ( 'opacity', '1' ).bind ( 'click', runReport );
    }
});
If anyone has any thoughts on what might be happening, I'd really
appreciate it. I Googled until my fingers bled, but couldn't find
anything that seemed to make a difference. I'm hoping that maybe I've
just been looking at it for too long and am missing the obvious.
Thanks.
Rob Wilkerson