Why can I not ping other servers in the same network?

Hi All,

I've got a basic domain setup.  All VMs are on the same network.  All VMs are on the same domain.  One VM is a DC (Windows 2008 R2).  Server A and B are Windows Server 2008 R2.

I am having trouble pinging the servers (A or B) from each other.  Sometimes it works, sometimes it doesn't.  The results are random.  When I ping by computer name I see the FQDN return so I know it's seeing the DNS server but I get the "Request timed out".  I often get the same results when I try to ping by FQDN or IP.  However, sometimes I can successfully ping.  Firewalls on both machines are turned off.

I'm not sure of what to do at this point.

Suggestions?

Thanks