JSI Tip 7631. SQL Server Windows XP clients are authenticated as guests if Simple File Sharing is enabled?

When you attempt to register a server in SQL Server Enterprise Manager, or you attempt to connect to SQL Server 2000 by using SQL Query Analyser, AND your computer is NOT in a domain, you receive:

Login failed for user <ServerName\guest>

This problem occurs because all remote users are authenticated as quests to SQL Server 2000 when Simple File Sharing is enabled.

NOTE: See How do I disable Simple File Sharing on Windows XP Professional?