Ok will try to give as much detail as possible.
Recently users of a small SBS 2003 network have complained they are being disconnected from the network. They are working away fine on a database application which runs from the server and all of a sudden they get disconnected from both the application and from email when they browse through my network places and click on entire network and select their domain they receive "domainexample is not accessible you might not have permission to use this network resource. they cannot get to the server via unc or ip address. The SBS is set as their primary dns, it fails when they do an nslookup, they can browse the web fine as this goes through the firewall. The disconnect might only last a couple of seconds to a few minutes. The server is fully patched and there is no errors in een viewer to indicate any problems, I have run diagnostics on the network card and they all come back fine.
When the network went down I was unable to ping the firewall from the server however I was able to ping the firewall from a laptop connected into the same switch as the server ??! so the problem seems to point to the server but as event viewer is not displaying anything related and I have run a network analyzer which doesn't appear to highlight anything abnormal I'm stuck!