Missing Resource - WebResource.axd call returning a 404, and

We are working with SiteFinity 4, hosted on DiscountASP.net.  On a irregular (less than 5 minutes between cycles with 5 editors working) schedule, we will see the following error logged to the Errors.log file:

----------------------------------------

Timestamp: 1/15/2011 2:13:49 AM
    Message: This is an invalid webresource request.

   at System.Web.Handlers.AssemblyResourceLoader.System.Web.IHttpHandler.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

    Category:
    Priority: -1
    EventId: 1
    Severity: Information
    Title:
    Machine: THEBEAST
    Application Domain: /LM/W3SVC/2/ROOT-3-129395257431489152
    Process Id: 3972
    Process Name: c:\windows\system32\inetsrv\w3wp.exe
    Win32 Thread Id: 8980
    Thread Name:
    Extended Properties:

----------------------------------------

If we investigate in the web logs, we find this call:

2011-01-15 02:13:49 172.27.41.70 GET /WebResource.axd d=p8clnff8LmQ_WksB8TlY33EzXQDw6XhSZQcm-lKumpMGlB7r88147nIUqByjox4i5-8zP0nF8OO6LLEeyjSki70SSE8wBgTM0ItyW1v6avD_V2Rhu9_Lnahp6D1W3XPojP8RkmonoACo4LNkpLo9ae51wlGyiSa-vWanM5QC5hHngL8CF7myvyVJ4Vyfx45R0&t=634306222809563743 8888 cssteam 172.27.40.199 Mozilla/5.0+(Windows;+U;+Windows+NT+5.1;+en-US)+AppleWebKit/534.10+(KHTML,+like+Gecko)+Chrome/8.0.552.237+Safari/534.10 404 0 0 170

Which is a 404, looking for a resource.  If we decode the resource URL we get:

pTelerik.Web.UI|Telerik.Web.UI.Skins.Sitefinity.ToolBar.rtbDropDownBg.png

And if we open up Telerik.Web.UI with Reflector, this resource is indeed missing.

Any way to stop this from cratering our work all the time?

Hi Chris,

Thank you for contacting us. 
I am really sorry to hear about this problem. Could you please provide us with a url to your web site, and tell us on which page it is happening? If you want to keep this in private, please open a support ticket.

Thank you in advance.