The mysterious 'Account Unknown' displayed in Security properties

[Guest]

Dear all,

I have shifted through various Google searches in an attempt to discover
more about this interesting discovery I made recently when viewing the
security properties of my own and another user's folders in 'C:\Documents and
Settings\'. In both cases the security tab displayed a user 'Account Unknown
(S-1-5-21-682...)'. All this tells me so far is that Windows XP is unable to
resolve the specific SID to an account name.

This hasn't presented me with any problems and for the most part I am
posting here out of curiosity, perhaps to enquire if I can safely click the
'Remove' button on this account in the security tab, although if it isn't
broke, don't fix it... right?

I currently have a dual boot with XP Pro and Vista RC1 on the same hard
drive. On one ocassion I tried to access my own files in my account on the XP
install from within Vista. I seem to recall that I couldn't access any
further than 'C:\Documents and Settings\Carl\' i.e. I couldn't get into My
Documents which was where I wanted to gain access. Although Vista presented
me with the option to take ownership I declined out of fear of messing with
my own account in XP and learnt to place certain files elsewhere.

My theory is, might my attempted access via Vista have generated an 'access
control entry' (ACE) and thus placed my Vista account into the security
information of these folders. If this is the case, can I just safely delete
the references to this account in the securty tab? Also, is there a way I can
easily access such folders from Vista? When I passworded my account I chose
to make my documents private so I am assuming this is the likely explanation
for me not being able to access them in Vista, in which case, does it seem
wiser to remove this restriction or is there a work-around?

 

[Pegasus \(MVP\)]

Dear all,

I have shifted through various Google searches in an attempt to discover
more about this interesting discovery I made recently when viewing the
security properties of my own and another user's folders in 'C:\Documents and
Settings\'. In both cases the security tab displayed a user 'Account Unknown
(S-1-5-21-682...)'. All this tells me so far is that Windows XP is unable to
resolve the specific SID to an account name.

This hasn't presented me with any problems and for the most part I am
posting here out of curiosity, perhaps to enquire if I can safely click the
'Remove' button on this account in the security tab, although if it isn't
broke, don't fix it... right?

I currently have a dual boot with XP Pro and Vista RC1 on the same hard
drive. On one ocassion I tried to access my own files in my account on the XP
install from within Vista. I seem to recall that I couldn't access any
further than 'C:\Documents and Settings\Carl\' i.e. I couldn't get into My
Documents which was where I wanted to gain access. Although Vista presented
me with the option to take ownership I declined out of fear of messing with
my own account in XP and learnt to place certain files elsewhere.

My theory is, might my attempted access via Vista have generated an 'access
control entry' (ACE) and thus placed my Vista account into the security
information of these folders. If this is the case, can I just safely delete
the references to this account in the securty tab? Also, is there a way I can
easily access such folders from Vista? When I passworded my account I chose
to make my documents private so I am assuming this is the likely explanation
for me not being able to access them in Vista, in which case, does it seem
wiser to remove this restriction or is there a work-around?

Unknown accounts are shown in the security setting when
that account no longer exists. You can easily test this:
1. Create a test account.
2. Give it some permissions to access a certain folder.
3. Delete the account from the Command Prompt with
this command: net user test /del
4. Check the permissions for the folder from Step 2.

You can safely delete such accounts from the security settings.

 

[Guest]

Thank you for your prompt reply Pegasus; you did answer my most important
question, however I would be grateful if you could just confirm the following:

I have never actually deleted a user account within Windows XP, so the fact
an unknown account is listed in the security tab must mean it is the account
I was logged in to when I attempted to access the folder within Vista,
correct?

I can only find two folders with reference to this unknown account on my
entire XP drive; namely the two different user accounts in Documents and
Settings, which must be the only folders I ever had difficulty accessing from
Vista.

 

[Guest]

Sorry about the ambiguity of my last comment, I mean to say; those two
folders are the only folders I 'have' ever not been able to access from
Vista. I am assuming this is not just coincidence.

 

[Pegasus \(MVP\)]

See below.

Thank you for your prompt reply Pegasus; you did answer my most important
question, however I would be grateful if you could just confirm the following:

I have never actually deleted a user account within Windows XP, so the fact
an unknown account is listed in the security tab must mean it is the account
I was logged in to when I attempted to access the folder within Vista,
correct?

You're probably right.

I can only find two folders with reference to this unknown account on my
entire XP drive; namely the two different user accounts in Documents and
Settings, which must be the only folders I ever had difficulty accessing from
Vista.

You can access any folder if you do this:
1. Log on under an administrator's account.
2. Seize ownership of that folder.
Click Start / Help and type "Ownership" to find out how to seize ownership.