Hi,Users are having problems to access our Exchange Server using WebAccess or Outlook HTTP access.I found lots of audit logon failures of users with error code0xC0000064 that means the account does not exist! But those accounts exists and after several attempts or a later attempt they enter.I'm trying to know what's the cause for that logon failures.We have a Win2000 server that that is the DC, and a Win2003 Server with the Exchange Server.The internet router directs HTTP to the Exchange server, where we have also the IIS with Exchange webaccess.How can I solve this problem? Does anyone knows what is the problem?How can I give you more information to help you helping me?The audit message is (I'm sorry, it's in portuguese, but I think it can help): Tipo de evento:Auditoria sem xitoOrigem do evento:SecurityCategoria do evento:Incio de sesso de conta ID do evento:680Data:12/02/2009Hora:0:19:10Utilizador:NT AUTHORITY\SYSTEMComputador:TELECASTERDescrio:Tentativa de incio de sesso por: MICROSOFT_AUTHENTICATION_PACKAGE_V1_0Conta de incio de sesso: rpereira@mydomain.ptEstao de trabalho de origem: PT26PCdigo de erro: 0xC0000064Thanks,Pedro Gonalves

Hi, It seems this issue is related to Exchange Server. I suggest discussing it in our Exchange Server forum. They are the best resource to troubleshoot this issue. Exchange Server forum: http://social.technet.microsoft.com/Forums/en-US/category/exchangeserver/ I hope your issue can be resolved soon. Tim Quan - MSFT