Windows 8.1
Mcafee resident anti virus



In last free spybot, the lockdown registry feature:

A) is really effective?, intruders and malware do not yet know how to handle it?
B) cannot give any problem, like rendering impossible necessary registry changes when downloading windows updates or new programs , changing preferences or settings or other?
C) Can I be easily undone by the pc administrator (and not by malware or intruders)? how?
D) does it operate thru changing the value in the registry to make unable the regedit tool? if so, how can regedit be enabled again?