When I log on using correct user name\password (I always copy-paste them) I get 401.1 error. User name and password are correct (user is created on server locally, not a domain one). I can run program as this user (runas /noprofile /user:tmp notepad.exe). Basic authorization's default domain is a server name, realm is empty. I've saved FailedReqLogFile. AUTH_BASIC_LOGON_FAILED shows ErrorCode="Logon failure: unknown user name or bad password. (0x8007052e)" and MODULE_SET_RESPONSE_ERROR_STATUS shows ModuleName="BasicAuthenticationModule", Notification="AUTHENTICATE_REQUEST", HttpStatus="401", HttpReason="Unauthorized", HttpSubStatus="1", ErrorCode="Logon failure: unknown user name or bad password. (0x8007052e)", ConfigExceptionInfo="" And one more thing - if I use my domain login\password it woks! Basic Authentications is only enabled authentication in application... Could you please suggest me how I can troubleshoot and fix this issue? Maybe somebody hit it before... Best regards, Alex UPDATE: I get 401.1 when I trying to access site from local host. I can actually access files from remote host.