AppleShare IP 6.0: Windows Client Logged In As Guest

When I connect to our AppleShare IP 6.0 (ASIP) server from a Windows client via SMB, sometimes it seems that I have lost my user privileges. Further inspection shows that I only have guest access. Why is this?
This may happen if guest access is enabled and if you misentered your user name or password. Instead of denying access, ASIP will log the user in with guest access.

For further information on the ASIP 6.0 logon behavior for Windows File Sharing (SMB) clients, please see the following Tech Info Library article:

Article 24620: "AppleShare IP 6.0: SMB Logon Behavior"
Published Date: Feb 18, 2012