When you join a Windows 2000 computer to a domain, you may notice a substantial growth in the size of the registry. If it becomes too large, Windows will not start, and you receive:
Windows 2000 could not start because the following file is missing or corrupt: \WINNT\SYSTEM32\CONFIG\SYSTEM.
NOTE: This behavior may also occur when you log on to a domain member.
This behavior can occur if Group Policy is used to apply large and complex DACL (Discretionary Access Control List) entries to a registry hive, because the SCE (Security Configuration Engine) applies and removes permissions as it propagates through various inheritance settings, causing fragmentation of the registry hive.
NOTE: You should attempt to reduce the complexity of the DACL settings that you apply to registry hives via Group Policy.
To workaround this problem:
1. Boot the Recovery Console.
2. Type the number for the appropriate Windows installation and type the Administrator account password.
3. At the Recovery Console command prompt, type the following, pressing Enter after each command:
ren system system.old
copy system.old system
NOTE: When you copy the hive, only the data is copied, eliminating the 'white space' fragments.