Client user timeout

Hi,
Used Mssql 5 exp. On win 2003 server
my problem,
client user time out 15 minute by sql server,
Client user inside my program, connection closed,
logout program and relogin program work again,
no network problem, no closed network connection
How can i do,There are several reasons depending upon how the connection process is set
up. For a brief review see: http://vyaskn.tripod.com/watch_your_timeouts.htm
Anith