Multiple DNS servers using in the local network

Multiple DNS servers using in the local network

i am not well speaker in english. So pls don't mention.I am using windows
server 2008 and it is domain controller. i am using one more server that
is windows SBS server 2003. the windows server 2008 is migrated from the
windows SBS server 2003. It is working fine and there is no network issue.
But i added new windows SBS server 2003 with in this network and domain is
also created in this server and also created DNS server. The domain
created for in this SBS server for it is automatically shutdown with out
domain control.
I shared some folder for software purpose in newly added SBS server 2003.
That folders are mapped to client systems.
There after this server added i am getting network issue. The mapped share
folder (from the SBS server) working some time and some time unable to
open error is coming. Then i disconnect the mapped folder and reopen the
newly added SBS server and give username and password then map again
shared folders.
I am doing this job many times. Right now i am using one windows server
2008(domian controller) and one SBS server 2003 (member server) and one is
SBS server 2003 (Created domain controller for without get automatically
shutdown)
So please help me what to do i am.