Last weekend I upgraded my company net from 100mg to 1 gig (new firewall/router; all new cabling). Small net: 4 machines/peer-to-peer. All machines are Windows 7 64 bit. We use my machine as a sort of server (not domain) for the accounting software (Quickbooks) as well as document files (all vendor invoices).
Let me make some defs so you can follow:
Workstation 1: my machine: hosts the accounting data base as well as all the scanned documents.
Workstation 2: one of the interior designers
Workstation 3: another one of the inter designers
workstation 4: retail store check out.
Routine plan: workstation 1 stays on all the time. Others shut off at end of day. In the morning, workstation 2 usually cranks up before others arrive.
Since upgrading the net, if we fail to launch workstation 4 AND connect it to the accounting database on workstation 1, workstation 3 takes on the identity of workstation 1 but doesn't host the accounting database causing workstation 4 to be unable to connect to the accounting database. (When you go to the network and click on workstation 1 you actually see the icons for workstation 2).
If I shut workstation 2 down (cold) then workstation 4 readily connects to the database on workstation 1. Once re-booted, workstation 2 happily goes about its duties.