After reading that not only these subsystems are not commonly used but also they can slow down the system, I decided to remove them. I tried to delete the winntsystem32os2 folder but had to do it in Safe Mode. Also I tried to rename 3 files in the winntsystem32 but they kept coming back and are still around. Finally as indicated in the article at LabMice.net (Windows 2000 Security Checklist), I made changes to the registry (see below). However, Windows 2000 keeps putting back some of these keys in the registry. What should I do to get rid of these subsystems?
Thanks. Dom

Use the Registry Editor to remove the following registry entries:

Key:
HKEY_LOCAL_MACHINESOFTWARE

Subkey:
MicrosoftOS/2 Subsystem for NT

Entry:
delete all subkeys


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Key:
HKEY_LOCAL_MACHINESYSTEM

Subkey:
CurrentControlSetControlSession ManagerEnvironment

Entry:
Os2LibPath

Value:
delete entry


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Key:
HKEY_LOCAL_MACHINESYSTEM

Subkey:
CurrentControlSetControlSession ManagerSubSystems

Entry:
Optional

Values:
delete entry


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Key:
HKEY_LOCAL_MACHINESYSTEM

Subkey:
CurrentControlSetControlSession ManagerSubSystems

Entry:
delete entries for OS2 and POSIX