WorkGroup Issue.....

When opening "My Network Places" and clicking on the
link "View Workgroup Computers" I get the following
message.

"Workgroup is not accessible. You might not have
permission to use this network resource. Contact the
administrator of this server to find out if you have
access permissions.

This account is not authorized to log in from this
station."

There is another computer in the workgroup....that has
file sharing enabled. I can not even see the other
computer, this error is not coming up when i am trying to
access a share.

I was able to access the computer before without issue. I
did rebuild this machine recently I am not sure if that
had something to do with the problem.

Thanks for any help.