Task Manager has been disabled

Solution 1
Click Start, Run and type this command exactly as given below: (better - Copy and paste)
REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableTaskMgr /t REG_DWORD /d 0 /f

Solution 2
• Click Start, Run and type Regedit.exe
• Navigate to the following branch:
HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies\ System
• In the right-pane, delete the value named DisableTaskMgr
• Close Regedit.exe

Solution 3:
Using Group Policy Editor - for Windows XP Professional
• Click Start, Run, type gpedit.msc and click OK.
• Navigate to this branch:
User Configuration / Administrative Templates / System / Ctrl+Alt+Delete Options / Remove Task Manager
• Double-click the Remove Task Manager option.
• Set the policy to Not Configured.