Check this thread where a similar problem was solved:
 
http://www.ntcompatible.com/vb/showthread.php?threadid=15079&highlight=cdrom
 
Hope this helps.

Hi, wolf:
 
Thanks for your hint. But the problem is: i can not even locate
my CDROM drive in device manager. There is nowhere showing hardware
conflict. It seems the system can not find DVD at all. But i
can see it listed in BIOS configration. I also able to use the CDROM
if i booted in DOS mode.
 
Thanks for your attention!!

Checked here:
 
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contr
ol\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}]
 
"UpperFilters"= Cdralw2k
"LowerFilters"= CDr4_2k
 
 
C) After a right click on My Computer, Manage, Storage, Removable Storage, Physical Locations, do DVD-ROM appear?
 
my drives appear in Physical Locations under removable storage, but they have a red "X" on the left side of them. But there isnt a mention of what type of problem there.
 
But i do not know how to make an expand. My W2k CD start up automatically installation and can not allow me to expand CDsys file.
 
Could you give me more hint?
 
I have tried to remove CDr4_2k from the registry key value and rename
file CDr4_2k.sys to CDr4_2k.sy_ but still not solve the problem.

That means the DVD drivers are available on hard disk but something interferes and prevents activation.
 
Check this note about complete removal of ECDC Registry entries on a Windows 2000 system:
 
http://205.162.50.212/tips/cdr_and_win2k.shtml
 
Reinstallation of Aspi drivers is a safe move:
 
http://www.cyrus.troy.btinternet.co.uk/downloads.htm

Thanks again for your help!
 
But it seems reinstall of APCI layer is not helpful.
 
I did installed a UDF CD reader downloaded from website,
I tried to clear the key mentioned in the articel but seems not
work things out.
 
I am trying to recover cdrom.sys but i do not know how i
can get the file since the CD can not recognized by the system.
 
again i can not see CD listed in Device Manager.
 
I can reinstall the system, but i would like to understand
the real reason that causing this incase i am running into this again.
 
Got any more hints? Thanks!

Clearly the only solution is to reactivate the standard associations found in the Windows 2000 Registry. They are all included in the following lines. They normally link CD and DVD file system drivers and the CD and DVD hardware drives. Please copy these lines to a Notepad file; name it CD_install.reg. Then make a complete back up of your registry. Double click or right click on CD_install.reg and Merge in Registry. Reboot and check DVD.
 
 
 
Windows Registry Editor Version 5.00
 
[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}]
"Class"="CDROM"
@="DVD/CD-ROM drives"
"EnumPropPages32"="MmSys.Cpl,MediaPropPageProvider"
"Installer32"="storprop.dll,DvdClassInstaller"
"SilentInstall"="1"
"NoInstallClass"="1"
"TroubleShooter-0"="tshoot.chm,hdw_drives.htm"
"Icon"="-51"
"LowerFilters"=hex(7):63,00,64,00,72,00,34,00,5f,00,32,00,4b,00,00,00,00,00
"UpperFilters"=hex(7):70,00,77,00,64,00,5f,00,32,00,4b,00,00,00,00,00
 
[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}\0000]
"DefaultDvdRegion"=dword:00000001
"EnumPropPages32"="storprop.dll,DvdPropPageProvider"
"InfPath"="cdrom.inf"
"InfSection"="cdrom_install"
"ProviderName"="Microsoft"
"DriverDateData"=hex:00,40,99,31,33,2e,bf,01
"DriverDate"="11-14-1999"
"DriverVersion"="5.0.2183.1"
"MatchingDeviceId"="gencdrom"
"DriverDesc"="CD-ROM Drive"
 
[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}\0001]
"DefaultDvdRegion"=dword:00000001
"EnumPropPages32"="storprop.dll,DvdPropPageProvider"
"InfPath"="cdrom.inf"
"InfSection"="cdrom_install"
"ProviderName"="Microsoft"
"DriverDateData"=hex:00,40,99,31,33,2e,bf,01
"DriverDate"="11-14-1999"
"DriverVersion"="5.0.2183.1"
"MatchingDeviceId"="gencdrom"
"DriverDesc"="CD-ROM Drive"
 
[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}\0002]
"DefaultDvdRegion"=dword:00000001
"EnumPropPages32"="storprop.dll,DvdPropPageProvider"
"InfPath"="cdrom.inf"
"InfSection"="cdrom_install"
"ProviderName"="Microsoft"
"DriverDateData"=hex:00,40,99,31,33,2e,bf,01
"DriverDate"="11-14-1999"
"DriverVersion"="5.0.2183.1"
"MatchingDeviceId"="gencdrom"
"DriverDesc"="CD-ROM Drive"

Hi,
 
I desperately reinstalled the whole system.
Now everything is working.
 
Just when i installing the Intel IDE Ultra
driver when i realized my problem:
 
i removed one ATA100 device driver one day.
(when i see there is two ATA100 device so i
just stupidly delete one)
That actually killed my 2nd IDE interface.
I think that is the reason that the system
can not locate DVD drive. So the solution could
be reinstall ATA driver and get the CDROM back.
 
It seems a pretty reasonable reason for me.
But anyway i reinstalled the whole system.
It's running great now and thanks agian for
your kind help.