Hello,
This number represents an account being granted access to that folder.
In Windows, your user account (such as "Smitty") is represented internally
as a long string of numbers (like the one you mentioned). Therefore, a user
named smitty on one installation of Windows will have a different number
than a user named smitty on a different installation of Windows, even if
these installations of Windows are on the same computer.
So, if you look at the security on a file that was created on another
computer, created from a different installation of Windows, or you have
given yourself access to the file from another installation of Windows, you
will see a number instead of an account name, since that number represents
an account on another installation of Windows and is only meaningful from
that other Windows installation.
--
- JB
Microsoft MVP - Windows Shell/User
Windows Vista Support Faq
http://www.jimmah.com/vista/