Question : Account Unknown in 2003 Server

Under the Security Tab of Documents and Settings Properties in 2003 Server, I see an account titled [Account Unknown (S-1-5-32-547)]. This account doesn't show up anywhere in AD U&C. Any ideas if this should be there or am I being hacked?

Answer : Account Unknown in 2003 Server

Looking at a DC I recently promoted, I see that same SID listed as well.  A DC does not have a local Power Users group like a standalone server does.  A default install of 2003 will have that group, which would be a part of the default ACL on files and folders (including Docs and Settings), so when you promote the server to a DC and the local groups are effectively replaced with domain groups the server won't be able to enumerate local group SIDs such as that which remain on file and folder ACLs.  It's just a holdover from before you promoted the server to a DC, you can safely delete it.

-BR