PageRequestManagerServerErrorException: Conversion from string to type 'Date' is not valid

hello,

I am having some real trouble with this one.  I have an aspx 3.5 page that submits a record to a backend sql server 2008 database.  When I test this page on my local testing server for asp with a real connection to the live database everything works.  But once i copy the file to the live website and try to insert the record from the live aspx file i get the following error:

  Sys.WebForms.PageRequestManagerServerErrorException: Conversion from string "14/09/2010" to type 'Date' is not valid

internet explorer debugger shows that the error is being thrown in the following code from the microsoft ajax on the line "finally {"

// Name:        MicrosoftAjax.debug.js
// Assembly:    System.Web.Extensions
// Version:     3.5.0.0
// FileVersion: 3.5.30729.196
//-----------------------------------------------------------------------
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------
// MicrosoftAjax.js
// Microsoft AJAX Framework.


//other code removed to keep this short
Sys.Net.XMLHttpExecutor = function Sys$Net$XMLHttpExecutor() {
    /// <summary locid="M:J#Sys.Net.XMLHttpExecutor.#ctor" />
    if (arguments.length !== 0) throw Error.parameterCount();
    Sys.Net.XMLHttpExecutor.initializeBase(this);
    var _this = this;
    this._xmlHttpRequest = null;
    this._webRequest = null;
    this._responseAvailable = false;
    this._timedOut = false;
    this._timer = null;
    this._aborted = false;
    this._started = false;
    this._onReadyStateChange = (function () {
        
        if (_this._xmlHttpRequest.readyState === 4 ) {
            try {
                if (typeof(_this._xmlHttpRequest.status) === "undefined") {
                    return;
                }
            }
            catch(ex) {
                return;
            }
            
            _this._clearTimer();
            _this._responseAvailable = true;
            try {
                _this._webRequest.completed(Sys.EventArgs.Empty);
            }
            finally {
                if (_this._xmlHttpRequest != null) {
                    _this._xmlHttpRequest.onreadystatechange = Function.emptyMethod;
                    _this._xmlHttpRequest = null;
                }
            }
        }
    });
    this._clearTimer = (function() {
        if (_this._timer != null) {
            window.clearTimeout(_this._timer);
            _this._timer = null;
        }
    });
    this._onTimeout = (function() {
        if (!_this._responseAvailable) {
            _this._clearTimer();
            _this._timedOut = true;
            _this._xmlHttpRequest.onreadystatechange = Function.emptyMethod;
            _this._xmlHttpRequest.abort();
            _this._webRequest.completed(Sys.EventArgs.Empty);
            _this._xmlHttpRequest = null;
        }
    });
}

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I have no idea what the above code is doing as I don't know java script and this is the last problem I have to fix before I can make the site live for my clients.

Any help at all is greatly appreciated