Question : Workstations on domain lose connection after about 10 hours passes

I am running MS Server 2003 and a network of about 7 XP clients. The clients lose there connection to the server after a certain period of inactivity. I have tried changing the group policy by disabling kerberos 10 hour policy but i put it back on, disabling the power management of the Nic cards on all workstations and server. I also ran the net config server /autodisconnect:-1 cmd on server and didn't work.
Today- I also changed the whole ipscheme from the workstations being static to dynamic and just switched them today to pull dhcp from the server and not from the router so they point default dns to the server and use ip fowarders on server to get external dns.  I don't know if the change today worked but we will see.  Any ideas?  after so much time of the day, the workstations lose connection to their mapped drives and to phoneslips but the local area connection does not drop.            forgot to add if they restart it goes away                  any ideas?

Answer : Workstations on domain lose connection after about 10 hours passes

we have fixed the problem so far. the solution was to make the workstations dhcp but also move the dhcp server to the server and let the server be the local dns using ip fowarders to get the workstations outside for external requests.  the mapped drives are not losing connections everyday now.  
My question is why did it do it before? hope this can help people.