I am trying to connect the Instance of SQL Express 2005 from a client PC (running on Windows XP).
While in the Object Explorer connection window, I can view the required SQL Express Instance installed in my server, but while i try to connect the instance, it says 'Login failed for the user 'MYSERVER/guest'
The same error popups when i try to tun my client application (developed in VB6)..
The server is set to run on Windows Autentication Mode and i've enabled the TCP/IP in the Local and Remote connections in Surface Area and the TCP/IP is enabled.
'Login failed for the user 'MYSERVER/guest'
The server is set to run on Windows Autentication Mode
This would suggest that your clients windows logon is unknown - hence the first line.
When connecting, change to SQL Server authentication and use an account you have already set up on the server (your own perhaps?) - this might help narrow down the issue.