I have two XP computers with the same problem, I can not access Control panel or Regedit all I get is "canceled due restriction...call your administrator" for Control Panel and Regedit disappears after a few seconds when I try to run it. I called my admin and he said he didn't put any restrictions on any of the computers.
I managed to bring back Control Panel icon in start menu via Group Policy settings but I still cant use it, I get the same message as before.
So my question is - does this look like malware or someone just played with restriction settings?
What are the best tools to use to fix this kind of problem? Any ideas?