when i press alt+ctrl+del or shift+crtl+esc it shows the msg as "task manager has been disabled by ur administrator"
plz tell me wht shud i do
thak u
kunal

By default (at least in WinXP) a User can bring up the task manager via Ctrl + Alt + Del.
If it has been disabled, the administrator (i.e. someone with Administrator rights) has done that.
If you are also Administrator you have disabled it yourself and thus know what to do.
If you are not Administrator, you cannot change security policies.
So: ask your administrator (or one of them).

http://www.kellys-korner-xp.com/xp_tweaks.htm

Line 51 on the right hand side. Enable Taskmanager. Download and install the file.

Joe

It would be a most interesting comment on Windows security if you could change system wide settings as a User via regedit, settings the Administrator has changed e.g. via the Local Security applet.