jQuery Grid Plugin - jqGrid

I have an implementation that works fine for IE9, Chrome, but causes IE6 to lock up ..  I set up a test environment (Oracle VM) with Windows XP and Internet Explorer 6.  JQGrid is configured to point at a WCF POST method.  Using Fiddler, I can see that the header request info looks ok, including content-length, but there is no post data in the body.  

Setting a breakpoint (on xmlhttprequest) in Fiddler, it doesn't get to the breakpoint.. it locks up IE6.

If I use the IE6 JQGrid triggered request header, and add the post data using Fiddler, the request completes ok.

Please advise, thanks!

Is this a known issue, or a configuration issue on my part?  I will paste the main part of the config, the format is messy though:

var date = new Date();

grid.jqGrid({

url: 'Loader.svc/GetData?'+date.getTime(), // - webinvoke post, append random to ensure ie doesn't cache

postData: { path: path },

search: true,

datatype: 'json',

mtype: 'POST',

ajaxGridOptions: { contentType: 'application/json; charset=utf-8', type: 'post' },

loadonce: true, // - load data once on server side, then switch to local data handling

serializeGridData: function (postData) // - process returned object from web-invoke to json

{

return JSON.stringify(postData);

},

jsonReader: { // - map json to grid elements ( this is how the grid expects the data from the server )

root: function (obj) { return obj.d.rows; },

page: function (obj) { return obj.d.page; },

total: function (obj) { return obj.d.total; },

records: function (obj) { return obj.d.records; }

},

rowNum: 15, // - rows per page

rowList: [5, 10, 15, 20], // - options for rows per page

pager: '#pager', // - element anchor for navigation panel

gridview: true, // - row at once binding (faster performance)

//rownumbers: true, // - numbering column at left of grid

autoencode: true, // - encode html data

ignoreCase: true, // - searches are case-insensitive

sortname: 'IDNumber', // - sort column for initial load

viewrecords: true, // - displays the beginning and ending record number in the grid, out of the total number of records in the query

sortorder: 'desc',

caption: 'Card Personalization',

height: '100%',

editurl: 'clientArray', // - normally the endpoint to post edits, in this case we just edit local data

shrinkToFit: false, // - defines how the width of the columns of the grid should be re-calculated, taking into consideration the width of the grid

autowidth: true,

multiselect: true,