all. I am using a jquery version 1.6.2. I do a ajax call like this:
var jqxhr = $j.post(myPHP, function() { alert(\"success\"); })
For me this problem was caused by a cross-domain issue. So I had a local html file (c:\test.html) and tried to get data from a server (localhost/servlet). When putting html on the server - the problem was gone.
c:\test.html