I have a really interesting problem that presented itself tonight when I was attempting to make some changes. I have a domain running in 2003 functionality (domain and forest level) with a 2008 R2 primary domain controller (which also does DNS, DHCP and WINS). My secondary domain controller is running 2003 and also does DNS, WINS and has some shared printers installed on it.
I was attempting to change the IP address of the 2003 domain controller and ran in to nothing but problems. Long story short I ended up moving it back due to all kinds of errors I was getting that could not be resolved with dns updates, dcdiag, netdiag, etc.
Everything seems to be working fine for the rest of the network, however I have a Windows 7 machine that cannot access the shared files and printers on the 2003 domain controller. It can ping the server and it successfully resolves the DNS names using either server (in other words it can still use the 2003 server for DNS), but if I attempt to connect to the server via a UNC path, it times out and fails. It doesn't matter if I use \\computername or \\computername.fqdn.tld - it fails every time. The really odd this is it will work for a few seconds right after boot, but stops working shortly after. I've also noticed that the problem is 2-way, meaning I can log in to the 2003 server and cannot access the PC via UNC.
I've also noticed that startup and logon is taking much longer than usual on this machine as well. I've double and triple checked IP settings on all servers and this PC making sure it wasn't referencing a bunk IP address, but everything is correct. I've also tried flushing the various caches (netbios, dns, arp, etc).
Does anyone have any idea as to what might be causing this? It's the only computer that is having difficulty so I suspect it's a setting somewhere but I cannot narrow it down.