I am using sql server 2008 r2.There are about 50 pc in my office connected in network by using LAN.In a sql server 2008 r2 express(installed in windows 8) i have created all users windows account with same name as their name in their PC and then created windows authentication user in sql server. Now all the users are able to connect to sql server using windows authentication through SSMS.

But now i am trying implement same for the another SQL server 2008 r2 express which is installed in windows xp sp3. So i created one windows authentication user of network PC. But it is not working when i try to connect to sql server using windows authentication from network pc message comes like "Login failed for user 'PC91\Guest'. " It is not recognizing the windows account of my pc. why it happens? Please tell me a solution.

1) Can you post the entire error message?

1. Make sure SQL Server Service is running
2. If a named instance, make sure SQL Server browser service is running
3. Make sure SQL Server is configured to allow remote connections
4. Examine the SQL Server error log for messages confirming that SQL is listening on the expected network interfaces and ports
5. Test server connectivity with PING from the client machine
6. Test port connectivity using TELNET or PowerShell to the server and port (from step 4) from the client machine.  For example
a. TELNET <server-name> 1433
b. PowerShell: 1433 | % { echo ((new-object Net.Sockets.TcpClient).Connect("YourServerName",$_)) "server listening on TCP port $_" }
7. Check firewall settings if step 5 or 6 connectivity test fails

Thanks to Dan Guzman.