Understand it to mean
run "regedit"
Select "Hkey Current User > Software > Microsoft >
Windows > Current Version > Policies > System"
Double click "Disable TaskMgr"
Change value to 0
Three ways to enable the Taskmanager.
Download and execute the registry edit file
Edit the registry key manually
Edit the GPO directive [XP Pro version only] http://www.mvps.org/sramesh2k/Taskmanager_error.htm
If you are the administrator and no one else could have
disabled the taskmanager, it was probably done by
a parasite, disinfect your system with any of these
programs.