When you try to access the Task Manager by pressing Alt+Cntrl+Deleteyou receive this error:
"Task Manager has been disabled by your administrator"
If you have Windows XP Pro,Click Start, then click Run and type ingpedit.msc
And press OK. This runs the Group Policy Editor.
Once in the Group Policy Editor, expand in turn:
User Configuration>Administrative Templates>System>Ctrl+Alt+Del Options
There is something like this:
Double click on Remove Task Manager to change its setting.It should be enough to click on Not Configured and then OK and Task Manager is available once again.