Entering Group and User Names

On a standalone computer or on a computer that is part of a workgroup and is not joined to a Windows domain, the list of available group and user names is drawn only from the account database on the local computer-that is, the computer at which you're logged on. If your machine is a domain member, you can click the Locations button and choose whether you want to specify permissions based on users of the local computer or those in the domain's directory. If you're entering names of users on a Windows domain, enter a portion of the name and then click the Check Names button.

Unfortunately, you can't use the same shortcut to select users and groups defined in the local computer's account database; instead, you have to enter the user's name in full, and if you're off by even a single letter you'll get an error message. (Windows will, however, fill in the computer or domain name for you automatically.) To see a list of available local users and groups, click the Advanced button, and then click Find Now. The resulting list includes all user accounts, groups, and special accounts on the local computer.

You can't change file or folder permissions

If you're unable to set custom permissions, look for the symptom in this list and try the following problem-solving techniques:

• The Security tab is not visible Do you see only a Sharing tab? If so, choose Tools, Folder Options, and clear the Use Simple File Sharing (Recommended) check box. If, after making this change, you still see only a Sharing tab, check the properties for the drive; the most likely explanation is that the drive is formatted using the FAT32 file system. The Security tab is visible only on NTFS drives.
• You've made changes, but the check marks disappear This may not be a problem at all. If you set permissions and apply them to anything other than the default location-This Folder, Subfolder, And Files-Windows adds a check mark in the Special Permissions box (when viewing permissions for a folder, you have to scroll to the bottom of the Permissions list to see this box). You can view the applied permissions by clicking Advanced, selecting the user or group, and clicking Edit.
• Permission settings are unavailable Check your user account rights. You must be logged on as a member of the Administrators group or be the owner of an object to set its permissions. These settings will also be unavailable if the selected object is inheriting its permissions from a parent folder. To set custom permissions on such an object, you have to remove the inheritance.