Logon servers unavailable

I installed windows 2003 standard edition as a domain
controlled with AD.
When i go to the network places i could see all the
machines in the LAN.
But when i try to browse this machines - It gives and
error---
" \\lanmachinename is not accessible you might not have
permision to use this network resource. Contact the
administrator of this server to find out if you have
access permission . Their are currently no logon servers
available to receive the logon request "

Appreciate if somebody could help me fixing this problem.
As i am running out of my production time

Thanks
Santhosh