Could you send the whole Header log in Firefox (firebug) or chrome (developer tools).
like this:
Request URL:http://localhost:81/paramquery/products.php
Request Method:POST
Status Code:200 OK
Request Headersview source
Accept:application/json, text/javascript, */*; q=0.01
Accept-Encoding:gzip,deflate,sdch
Accept-Language:en-US,en;q=0.8,es;q=0.6
Connection:keep-alive
Content-Length:182
Content-Type:application/x-www-form-urlencoded; charset=UTF-8
Cookie:PHPSESSID=5c7t0ltct2jto36ppe2stv6875
Host:localhost:81
Origin:http://localhost:81
Referer:http://localhost:81/paramquery/editing_batch.php
User-Agent:Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1700.102 Safari/537.36
X-Requested-With:XMLHttpRequest
Form Dataview sourceview URL encoded
addList:[{"UnitPrice":"10","Discontinued":false,"ProductName":"new ","QuantityPerUnit":"1","UnitsInStock":"1"}]
Response Headersview source
Cache-Control:no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Connection:Keep-Alive
Content-Length:249
Content-Type:text/html; charset=UTF-8
Date:Tue, 04 Feb 2014 12:01:23 GMT
Expires:Thu, 19 Nov 1981 08:52:00 GMT
Keep-Alive:timeout=5, max=100
Pragma:no-cache
Server:Apache/2.4.4 (Win32) PHP/5.4.15
X-Powered-By:PHP/5.4.15