After readin a few articles on it... I believe its not a problem. A security identifier (SID) is a unique value of variable length that is used to identify a security principal or security group in Windows 2000
Its part of the Windows 2000 NTFS File Encryption, and Windows NT and Windows 2000 Protected Storage etc
If its not a problem it may be best to leave it. But I am willing to stand corrected on this.