Workgroup access denied

Recently my domain controller went down. I decided to reconfigure my network
without a domain controller and use workgroups instead. 2 of the 7 computers
in my network are having problems.

On one I've changed the computer id info (in the properties page of the
local machine, under the local machine's administrator account) to the
workgroup, but dispite this change I'm unable to view the local workgroup or
access any of the computers in the workgroup. I get instead an access denied
message indicating I either don't have the correct permissions or that the
workgroup is unavailable.

The second errant machine will not allow me to change the network Id or
change to a work group because it can no longer find the domain controller to
remove the machine from the domain's active directory. This is preventing me
from adding the machine to the new workgroup.

In both cases I'm able to "ping" all the machines in the network so I know I
have connectivity. I've wasted hours searching the msdn knowledgebase,
without finding a single article that could apply to my problems.

Can you please give me some directions on how to resolve these two problems
and get my network operating properly.

--Larry