When Windows 2000 and Windows XP (both Home and Professional) begin the boot process, a 16 MB memory space is allocated for loading components needed for booting. These components include the boot loader, the kernel, the HAL, the drivers needed for booting and the System registry hive. If the hive exceeds 13MB in size, for whatever reason, Windows will fail to boot and generate the following error:
Windows could not start because \Winnt\System32\Config\System.ced is missing or corrupt.
The file in question is usually not, in fact, missing or corrupt (although it is possible, and shouldn't be ruled out). What has more likely happened is that due to several possible factors, the hive has grown too big to be loaded correctly, and must be replaced with an older (smaller) version. One common reason for this is an excess of system resource shares (stored in the Registry at: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\ Share). (For this reason it is not a good idea to use persistent shares, but rather to script them at login or startup; the net effect is exactly the same.)
To replace the System hive, boot into the Repair Console and enter the %windir%\system32\config directory, rename system to system.bak, and then rename system.alt to systemalt.bak. Next, copy in the backup of the system hive in %\windir%\repair\regback\system to windir%\system32\config. Note that this backup only exists if you have run the Emergency Repair Disk Wizard; if you want to copy in the default System hive, you can find a copy in %\windir%\repair\system.
Note also that any hardware drivers or programs that run as services will need to be reinstalled if you copy in the original hive. If you have installed any of these since the last time you ran the Emergency Repair Disk Wizard, you'll need to reinstall them as well if you use the backup hive created by the ERD.
Windows 2003's boot process has been rewritten to prevent or at least reduce the possibility of this happening. In Windows 2003, the System hive can be up to one-fourth the size of the physical memory, up to a maximum of 200 MB. (In systems with 3GB of RAM or more, the hive can be up to 110MB; in the 64-bit version of 2003, the total shared space for booting is 64 MB.)
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter. Check out his Windows 2000 blog for his latest advice and musings on the world of Windows network administrators – please share your thoughts as well!