scs- system log on

My enivornment is a win2003 server. 25 computers seem to log on fine every
morning, all shares, mapping and programs connect fine. HOwever for the last
3 weeks I have 3 machines that have been giving us intermitten issue. Every
once in a while we need to reboot the workstations in order for them to be
connected to the Server. Once rebooted all is fine thru out the day until we
restart again the next morning. It seens to happen about 3-4 days a week.
Twice other computers have had the same problem only once, never again.

It's driving us crazy and we can't see it becasue it happens once in awhile.

thanks for the help