Uninstalling Service Pack 4.

A. As was explained in "Q. Important steps for installing Service Pack 4.", Service Pack 4 makessome changes to registry which can't be undone. Because of this, in the eventof a Service Pack 4 uninstall the following files are left unrestored

Additionally the files below are also not restored:

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 securityonly), Rsabase.dll, Certmgr.msc, and Syske.exe.

To uninstall the Service Pack either start the Add/Remove programs controlpanel applet (Start - Settings - Control Panel - Add/Remove programs), select"Windows NT Service Pack 4" and click Remove, or, move to the%systemroot%$NtServicePackUninstall$spuninst directory and run spuninst.exe.

If you wanted to completely uninstall the service pack, undoing theregistry changes and restoring all original files you would need to restore the%systemroot% directory from a back and repair the registry using the ERD diskyou created. Alternatively you could uninstall as normal then use the ERD torepair the registry and replace the six files that the uninstall does not fix.