I have developed one windows application using SQLSERVER R2 Express as database.I installed application in 8 computers,and I installed sqlserver managements studio on their server(windows 2008 Os) and attached database "DB_data".My application in 5 computers are connecting to my database "DB_data" and working properly(windows7,XP service pack2 OS in 5 systems).But in three systems(its operating system XPservice pack2),It is not connecting with database,it is showing "time out error".I just created one .UDL file and tried to check connection.I could see the instance of SQLServer (ie.SERVER\PNRSQLSERVER),But when i tried to select database "DB_data",it is showing the following message "connection failed: SQLState:'HY100' SQL Server Error:0"

I dont understand what is the problem,Please guide me