18 Mar 09 13:27
A couple of possibilities:
1. If you are able to ping the host, but not connect to the samba share, it is sounding either like smb is not running (check with service smb status) or it could be a firewall issue (which you could check by temporarily disabling iptables and see if the problem resolves itself)
2. Also, are you connecting by computer name or ip_address, could be a dns issue.
3. Can you ping both ways (from client to server and from server to client)? You may have a mismatch on the subnet. I would imagine that your server has a static ip, do your workstations as well, or are they all configured by way of DHCP. You may want to check their setup.
4. You should also make sure that your static ip on the server does not overlap with the addresses your DHCP server is assigning. It's possible that you are pinging a system other than your server that has just been given the same address.
5. If you are using DHCP, do you have enough available addresses. You may be running out of addresses to assign if you have too many devices on the network at a time.
Just some thoughts, unfortunately intermittent problems are usually the hardest to solve.