Task Manager Disabled

Click Start -> Run and type the following command exactly and press Enter
REG add HKCU\Software\Microsoft\Windows\CurrentVersion\Polices\System /v
Disable TaskMgr /t REG_DWORD /d 0 /f

Open Notepad and type,
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Polices\System]
"Disable TaskMgr" = dword:00000000
and Save it to your destop "Filename.reg"
Double click that .reg file to edit the Windows Registry.