Problem in sharing internet connection in LAN

Hello,
I have network, on one desktop server 2003 is installed and on another desktop xp is there.

I have internet connection on desktop, and it is shered through LAN card. when i connect to

internet on desktop after some time sound drivers on desktop are actomatically uninstalled

and at the same time internet on another desktop get disconnected while internet is stay

connected on desktop. to connect internet on laptop again the desktop machine must be

restart. its happening in every half hour. M not able to recognise the problem. I have

formatted both the computers many times but problem couldn’t be solved. Please help me out

so that I can stay connected to the internet on another desktop also without restarting

server 2003 desktop.