When a group contains more than 500 users, the Person icon for the group becomes gray, to indicate that query operations may take a long time.
NOTE: This is an icon behavior for built-in groups, local groups, and global groups AND has no effect on functionality.
Using REG.EXE, built into Windows XP, Windows Server 2003, and later, or installed in Windows 2000 from the Support Tools on the operating system CD-ROM:
1. Open a CMD.EXE window.
2. Type the following command and press Enter:
REG ADD "HKCU\Software\Policies\Microsoft\Windows\Directory UI" /V GroupMemberQueryLimit /T REG_DWORD /F /D NUMBER
Where NUMBER is the new limit that you wish to set.
NOTE: Other Value Names of the Directory UI sub-key: