Hello,
after installing the Hot Fix for Microsoft Knowledge Base article number(s) 2553048 for Sharepoint 2010 SP1 i receive this error on default page.

Webpage error details

Message: ASP.NET Ajax client-side framework failed to load.
Line: 196
Char: 34
Code: 0
URI: http://srv-sp2010:30000/Pagine/default.aspx

Message: 'Sys' is undefined
Line: 223
Char: 1
Code: 0
URI: http://srv-sp2010:30000/Pagine/default.aspx

Message: 'Sys' is undefined
Line: 1371
Char: 1
Code: 0
URI: http://srv-sp2010:30000/Pagine/default.aspx

Message: 'Type' is undefined
Line: 2
Char: 1
Code: 0
URI: http://srv-sp2010:30000/_layouts/sp.core.debug.js?rev=Qp5K7ycU%2FEY9IvE0KOi7zQ%3D%3D

Message: Object doesn't support this property or method
Line: 5
Char: 3
Code: 0
URI: http://srv-sp2010:30000/_layouts/cui.debug.js?rev=%2BhQl2NTQMTydPivdG%2Bq%2FdA%3D%3D

I use in my master page:
<telerik:RadScriptManager ID="ScriptManager"  runat="server" EnablePageMethods="false" EnablePartialRendering="true" EnableScriptGlobalization="true" EnableScriptLocalization="true"/>
 if i change with scriptmanager i don't have error.
<asp:ScriptManager ID="ScriptManager"  runat="server" EnablePageMethods="false" EnablePartialRendering="true" EnableScriptGlobalization="true" EnableScriptLocalization="true"/>

I use Telerik version 2010.1.309.35

Thanks.

function collectSelectedItems() {
            var combo = $find("<%= radComboSource.ClientID%>");
            var items = combo.get_items();

            var selectedItemsTexts = "";
            var selectedItemsValues = "";

            var itemsCount = items.get_count();
            for (var itemIndex = 0; itemIndex < itemsCount; itemIndex++) {
                var item = items.getItem(itemIndex);
                var checkbox = getItemCheckBox(item);
                if (checkbox.checked) {
                    selectedItemsTexts += item.get_text() + ", ";
                    selectedItemsValues += item.get_value() + ", ";
                }
            }
            selectedItemsTexts = selectedItemsTexts.substring(0, selectedItemsTexts.length - 2);
            selectedItemsValues = selectedItemsValues.substring(0, selectedItemsValues.length - 2);
            //Set the text of the RadComboBox with the texts of the selected Items, separated by ','.
            combo.set_text(selectedItemsValues);
            document.getElementById("<%= radComboSource.ClientID%>").value = selectedItemsValues;           
        }

        function getItemCheckBox(item) {
            //Get the 'div' representing the current RadComboBox Item.
            var itemDiv = item.get_element();
            //alert(itemDiv);

            //Get the collection of all 'input' elements in the 'div' (which are contained in the Item).
            var inputs = itemDiv.getElementsByTagName("input");

            for (var inputIndex = 0; inputIndex < inputs.length; inputIndex++) {
                var input = inputs[inputIndex];

                //Check the type of the current 'input' element.
                if (input.type == "checkbox") {
                    return input;
                }
            }

            return null;
        }

function SRC_Changed(item) {
            var combo = $find("<%= radComboSource.ClientID%>");
            var items = combo.get_items();

            var itemsCount = items.get_count();
            for (var itemIndex = 0; itemIndex < itemsCount; itemIndex++) {
                var item = items.getItem(itemIndex);
                var checkbox = getItemCheckBox(item);
                if (checkbox.checked) {
                    var comboSTT = $find("<%= radComboSTT.ClientID %>");
                    var comboTYP = $find("<%= radComboTYP.ClientID %>");
                    var lblSTT = document.getElementById("<%= lblSTT.ClientID %>");
                    var lblTYP = document.getElementById("<%= lblTYP.ClientID %>");
                    var lblDAT = document.getElementById("<%= lblDAT.ClientID %>");
                   
                    if ((item.get_value() == "FAA") || (item.get_value() == "NTIA") || (item.get_value() == "CAN") || (item.get_value() == "CSM") || (item.get_value() == "AM") || (item.get_value() == "FM") || (item.get_value() == "TV") || (item.get_value() == "ARI") || (item.get_value() == "UNI")) {
                        comboSTT.set_enabled(false);
                        document.getElementById('<%= txtSTT.ClientID%>').disabled = true;
                        lblSTT.style.background = 'LightGray'
                        
                        var itemsSTT = comboSTT.get_items();

                        var itemsCountSTT = itemsSTT.get_count();
                        for (var itemIndSTT = 0; itemIndSTT < itemsCountSTT; itemIndSTT++) {
                            var itemSTT = itemsSTT.getItem(itemIndSTT);
                            var checkboxSTT = getItemCheckBox(itemSTT);
                            if (checkboxSTT.checked) {
                                checkboxSTT.checked = false;
                            }
                        }
                        comboSTT.set_text("");

                        comboTYP.set_enabled(false);
                        document.getElementById('<%= txtTYP.ClientID%>').disabled = true;
                        lblTYP.style.background = 'LightGray'
                       
                        var itemsTYP = comboTYP.get_items();

                        var itemsCountTYP = itemsTYP.get_count();
                        for (var itemIndTYP = 0; itemIndTYP < itemsCountTYP; itemIndTYP++) {
                            var itemTYP = itemsTYP.getItem(itemIndTYP);
                            var checkboxTYP = getItemCheckBox(itemTYP);
                            if (checkboxTYP.checked) {
                                checkboxTYP.checked = false;
                            }
                        }
                        comboTYP.set_text("");

                                           }
                    else if ((item.get_value() == "APP") || (item.get_value() == "AGN")) {

                        comboSTT.set_enabled(true);
                        document.getElementById('<%= txtSTT.ClientID%>').disabled = false;
                        lblSTT.style.background= 'white';

                        comboTYP.set_enabled(true);
                        document.getElementById('<%= txtTYP.ClientID%>').disabled = false;
                        lblTYP.style.background = 'white';
                       
                     }
                }
            }
        }