If you followed the steps in tip 785 » What steps should you take before installing SP4?, and understand the following notes, you will be able to remove or partially uninstall SP4.
Notes:
1. SP4 cannot be completely uninstalled using Control Panel / Add/Remove.
2. SP4 makes permanent changes to the Security Account Database and the Security Subsystem.
The only way to completely remove SP4 is to restore the %SystemRoot% folder and recreate of a new ERD. Run RDISK /S.
When you run the uninstall, SP4 leaves the following 6 files:
Samsrv.dll
Samlib.dll
Winlogon.exe
lsasrv.dll
Services.exe
Msv1_0.dll
The uninstall also fails to restore:
Crypt32.dll, Comctl32.dll, Schannel.dll, Cryptdlg.dll, Pstorerc.dll, Psbase.dll, Pstores.exe, Pstorec.dll, Cryptext.dll, Cryptui.dll, Mssign32.dll, Wintrust.dll, Softpub.dll, Mssip32.dll, Mscat32.dll, Initpki.dll, Cryptnet.dll, Xenroll.dll, Dssig.dll, Sigres.exe, Dssbase.dll, Reaenh.dll (128 bit security only), Rsabase.dll, Certmgr.msc, and Syske.exe.
If you don't have a backup, follow these steps to uninstall SP4.
1. Use Control Panel / Add/Remove and select Windows NT 4.0 Service Pack 4. Click Remove.
NOTE: You could also run $NtServicePackUninstall$\spuninst\Spuninst.exe
2. Use the ERD you created prior to the install to replace the 6 files.
3. Restore your previous $NtServicePackUninstall$ folder.
4. Check the SYSTEM Event Log for Event ID 4353, Source: NTServicePack, Description: Windows NT Service Pack 4 was uninstalled. Restoring Windows NT to Service Pack 3.
5. Create a new ERD by running RDISK /S.
