Can't set local security policy

[paquetjs]

I want to force users to type CTRL-ALT-DEL on the login screen before entering their usernames and pwds, and disable the display of the last username. I have done this before on other systems, I go in gpedit.msc - Computer Config - Windows Set - Security Set - Local Policies - Security Options. I try to change the "Don't display last username" and "do not require CTRL-ALT-DEL" and I get this error:

Security Templates:
Failed to save the Local Security Policy

I tried to go in the Security Config and Analysis snap in and set these properties from there, but this also fails:

Configure 
machine\software\microsoft\windows\currentversion\policies\system\disablecad.
Warning 5: Access is denied.
  Error configuring machine\software\microsoft\windows\currentversion\policies\system.
Configure 
machine\software\microsoft\windows\currentversion\policies\system\dontdisplaylastusername.
Warning 5: Access is denied.
  Error configuring machine\software\microsoft\windows\currentversion\policies\system.

I tried to change it manually in the registry, but no effect after a reboot. I am out of options now. I have never seen this type of error before. I am logged on as Administrator and the computer is not on a network of any kind. I do not see why I would not be able to edit the local security policies. Do any of you guys have an idea here. Thanks....

John

[benners]

You could check the read only attributes on the pol files in C:\WINDOWS\system32\GroupPolicy\Machine and make sure they are not read only.

[paquetjs]

that seems like a logical answer, but there are no files in that directory, the is a pol file in the user directory though, which is not read-only.