SharePoint AJAX Web Part 401.2/3 errors

Question

I recently began writing an AJAX web part for use in SharePoint and I am having a strange error. It seems that EnsurePanelFix() is causing the web part to throw a 401 error; in the log, both 401.2 and 401.3 errors are showing up right around the same time. I made some changes to EnsurePanelFix() after doing a bit of research on here and some other sites, and it is currently as follows:

void EnsurePanelFix
{
            // Change AJAX doPostBack behavior to fix the update panel.
            if (this.Page.Form != null)
            {
                String fixupScript = @"
                                     if (typeof(_spBodyOnLoadFunctionNames) !== 'undefined'){
                                     _spBodyOnLoadFunctionNames.push(""_initFormActionAjax"");
                                     function _initFormActionAjax() {
                                     if (_spEscapedFormAction == document.forms[0].action){
                                     document.forms[0]._initialAction =
                                     document.forms[0].action;
                                     }
                                     }

                                     RestoreToOriginalFormAction = function() {
                                     if (_spOriginalFormAction != null) {
                                     if (_spEscapedFormAction==document.forms[0].action){
                                     document.forms[0].action=_spOriginalFormAction;
                                     }
                                     _spOriginalFormAction=null;
                                     _spEscapedFormAction=null;

                                     document.forms[0]._initialAction = document.forms[0].action;
                                     }
                                     };
                                     }";

                string scriptKey = "UpdatePanelFixup";
                if (!Page.ClientScript.IsClientScriptBlockRegistered(scriptKey))
                    ScriptManager.RegisterStartupScript(this, typeof(SpecDatabaseViewer), scriptKey, fixupScript, true);

                ScriptManager.RegisterStartupScript(this,
                  typeof(SpecDatabaseViewer), "UpdatePanelFixup",
                  fixupScript, true);
            }

Watching the security log, I see that the failures are logged as such:

Event Type: Failure Audit
Event Source:   Security
Event Category: Object Access 
Event ID:            560
Date:       1/6/2010
Time:       11:46:34 AM
User:       NT AUTHORITY\NETWORK SERVICE
Computer:   SHAREPOINT
Description:
Object Open:
    Object Server:  SC Manager
    Object Type:    SERVICE OBJECT
    Object Name:    WinHttpAutoProxySvc
    Handle ID:  -
    Operation ID:   {0,69477107}
    Process ID: 404
    Image File Name:    C:\WINDOWS\system32\services.exe
    Primary User Name:  SHAREPOINT$
    Primary Domain: SPDOMAIN
    Primary Logon ID:   (0x0,0x3E7)
    Client User Name:   NETWORK SERVICE
    Client Domain:  NT AUTHORITY
    Client Logon ID:    (0x0,0x3E4)
    Accesses:   Query status of service 
            Start the service 
            Query information from service 

    Privileges: -
    Restricted Sid Count:   0
    Access Mask:    0x94

There are multiple failure audits with the only differing data between them being the operation ID.

Can anyone see any reason that I would be having authentication or file permission problems given that everything works fine without this piece of code? Thanks.

EDIT: I'm pretty sure that it has something to do with the ACLs, but I'm not exactly sure where to look for what resources may be causing the issue.

Answer 1

Can you catch, what URL exactly generates the 401.x errors? Must be visible if you intercept calls with Fiddler.

Also, this description seems very similar to your case: http://forums.asp.net/t/1187045.aspx