I'm getting an invalid viewstate error with regard to the ScriptResource.axd. Just wondering if anyone of you could help me on this. Error is:

2009-02-24 09:46:30,021 [13] DEBUG ASP.global_asax [(null)] - Request start - URL: /Web/ScriptResource.axd?d=E9hlvtsn8Gr1MyjysW1gFDFYr4CVwstY-sC22tRu5V8d7UyEYz3FhVYGrlhY87n2ihgKh58RrMRhK-Yk2WcQahEaCg_asTInqHK
2009-02-24 09:46:30,021 [13] DEBUG ASP.global_asax [(null)] - Application_AuthenticateRequest started
2009-02-24 09:46:30,021 [13] ERROR ASP.global_asax [(null)] - Unexpected error.  User presented with Site Error page.
System.Web.HttpException: Invalid viewstate.
   at System.Web.UI.Page.DecryptStringWithIV(String s, IVType ivType)
   at System.Web.UI.Page.DecryptString(String s)
   at System.Web.Handlers.ScriptResourceHandler.DecryptParameter(NameValueCollection queryString)
   at System.Web.Handlers.ScriptResourceHandler.ProcessRequestInternal(HttpResponse response, NameValueCollection queryString, VirtualFileReader fileReader)
   at System.Web.Handlers.ScriptResourceHandler.ProcessRequest(HttpContext context)
   at System.Web.Handlers.ScriptResourceHandler.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)

This happens in production environment. I'm unable to reproduce this in dev nor test environments. Also these pages can only be accessed by authenticated users. It would be really if you could shed some light on this matter.