Dropped network shares

I have a system running XP Pro SP2 with 2 shared folders and a shared
printer that the other computers in the workgroup (all XP Pro SP2) need to
access. The shared folders are mapped as drives on all the other computers.
We have been having a problem with the computer with the shared drives
disappearing from the network along with the shared printer. If we reboot
the computer it will usually reappear on the network. I have checked to see
if there are any scheduled tasks that might be running that would cause the
problem but there doesn't seem to be. Any help will be appreciated.

TIA, Gregg