Installed 2008 R2 server onto a network on existing 2003 server hardware (different HD's). Swapped HD's to 2008. Started 2008 server and all computer clients could see server fine (XP,s, Vista, Win 7's). Had up for about 7 hours. Shut down 2008 server, swapped back to 2003 server setup and now none of the clients can see the 2003 server. Did ipconfig /flushdns on a client and ipconfig /renew on a client and still not see 2003 server. Tried to UNC browse to server... no go. Linksys Router handing out DHCP with IP of server as one of the DNS's. Worked fine in this config before. What up?