can't see the domain controller after last update

Running W2K3 as domain controller and dns server. Have ISA 2004 installed on
W2K3. Installed SP1 on both 2K3 servers and SP1 on ISA 2004 over a month ago
with no issues. Basic configuration is DC/DNS server on internal lan, but
resolves internet ip requests. ISA is default route to WAN. DNS server
listed for ISA is internal DNS server defined on LAN nic. As of last
Thursday, no issues no problems. Now though in event log of ISA I have
errors:
1.The kerberos subsystem encountered a PAC verification failure. This
indicates that the PAC from the client <HFW> in realm <DOMAIN> had a PAC
which failed to verify or was modified. Contact your system administrator.
2.The session setup to the Windows NT or Windows 2000 Domain Controller <DC>
for the domain <DOMAIN> is not responsive. The current RPC call from Netlogon
on <HFW> to <DOMAIN> has been cancelled.
Internet connectivity is gone. Remote access to internal network is gone.
What is up? I have read of others having these problems right after
installing W2K3 SP1, but I did not. The problems just cropped up on
Thursday.