Delay in the TCP/IP stack for win 2003?

HI
I have an application that communicates to a device via a dedicated LAN, on
Win2000 all was fine but since going to Win2003 I loose my connection
once/twice a day.

When the device does not receive a response from the application for 10
consecutive real-time messages it re-sets the link. I can see that my
application is responding to the device but I think there is a delay in the
TCP/IP stack/NIC card in forwarding these responses.
Has anyone seen a similar delay in the TCP/IP stack for win 2003
--
Gordo