database connection time expired issue
Some things I'd check:


When you connect from SQL Server Management Studio 2008 on the box with Express, are you using the right server name (and possibly port number)?
Have you got Windows Firewall enabled on any of the machines?
Can you ping the SQL Server?  Do you get the same IP address for it that you get on the other machines?
Do you have any aliases set up in SQL Server Configuration Manager?
Have you disabled any client protocols in SSCM?