Sun Java Enterprise System 5 Release Notes for Microsoft Windows

User Unable to Log into he Web Console After Installing on Windows XP SP2 OS (6498436)

Workaround:

On Windows XP Professional, the guest account must be disabled.

The registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\ForceGuest must be set to 0 in order for authentication to succeed.