Hello ,I have a strange problem with an windows 2008 standard server , that is a memberofdomain.The domainoriginary have an windows 2000 sp3 domain controller ( mixed mode ) , that havealls fsmo roles , and a windows nt 4.0backup domain controller.We have added anwindows 2003 R2domain controller ( HP PROLIANT ML350 G5 server ),and a windows server 2008 standard X64 MEMBER SERVER ( HP PROLIANT ML370 G5 server ).The network communication work finefromthe domain controller ( WIN 2000 and also WIN 2003 ) and theWIN 2008 SERVER ( ping and network share ).The network communication also work fine from WIN 2008 Server to domain controller ,andalso internet ( with LINUX proxy server ).But from the CLIENT WINDOWS XP of the domain to the WINDOWS 2008 SERVER there is non communication ( The ping failed ) , and also from the WIN 2008 to WIN XP client.I have tried to disable WIN 2008 firewall , but the problem permain.Someone have an idea for help me ?

You are looking in the right direction with the firewall. I had this exact same problem and I think it has to do with ip security.Open Internet Explorer Properties (on the 2008 server) either in Internet Explorer by right clicking the IE icon on the desktop. On the Security tab, select the Local intranet zone. Click the Sites button, and then the Advanced button. Add your domain, with a wildcard, such as *.domain.dom,to the list of websites. Uncheck the box "Require server verification (https:) for all sites in this zone".I know this doesn't seem to be related, but think this is what did it for me. I think explorer uses the same settings as IE for ipsec.You can specify the "websites" using other formats, such as 192.168.2.*.