What is the SID ? - how many Computers have the Same SID in the domain? - when the SID cause problem? - How we can solve this problem?

The SID is a unique name (alphanumeric character string) that is used to identify an object, such as a user or a group of users in a networkof NT/2000 systems. Windows grants or denies access and privileges to resources based on ACLs, which use SIDs to uniquely identify users and their group memberships.

• SIDs are created when the account is first created in Windows and no two SIDs on a computer are ever the same.
• Users (you and me) refer to accounts by the account's name, like "Tim" or "Dad", but Windows uses the SID when dealing with accounts internally.
• The term security ID is sometimes used in place of SID or security identifier.