Those are the security identifiers (SID) of user accounts. The security
describor of an object holds access control lists (DACL and SACL) which consist
of access control entrys (ACE). In the ACEs the SID of the account is stored.
When a user tries to access a resource the ACEs of the resource are verified
against the SIDs of the user (his SID, SID-History and Group SIDs).
If you list the security of a resource and the System is not able to resolve
the SID to the User-/Groupname it displays the SID. This is possible when
either no domaincontroller is online/available to resolve the SID, or if a
Object has been deleted (unfortunately the System is not able to remove all
ACEs of all resources when a user or group is deleted).
So you can remove those S-1-5-... settings if you are sure that they are not of
a different domain of yours which is for some reason not online right now.
For more infos on SIDs see (URL may wrap):
Security Identifiers (Platform SDK: Security)
http://msdn.microsoft.com/library/en-
us/security/security/security_identifiers.asp
To prevent access control you'll have to remove everyone and authenticated
users.
Do you have a IIS installed on the system? Then you'll need them. If you don't
need the IIS I'd rather deinstall it.
You changed the permissions directly on the computer object in AD? This is not
the way to go and will AFAIK not provide you with the result you are looking
for.
I'd either create a OU in AD, and assign a Group Policy to that OU which will
change the security on the computers. This will be the way to go if you need to
set that group on more than one computer.
Or you can set this in the lokal group policy. Just start gpedit.msc, then go
to Computer Configuration -> Windows Settings -> Security Settings -> Local
Policies -> User Rights Assingment and adjust the groups in here.
Afterwards you'll either have to wait, or