Disable Right Click on the taskbar

Follow these steps:
Open Registry editor (start > Run> then type "regedit" (without quotes) and press enter button
this will open registry editor
then follow this path  ...
  HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ Explorer 

Now on the right pane right click and select a new>DWORD and give it the name "NoTrayContextMenu" (with out quotes) and double click on it and set its value to "1" (with out quotes). Log off or  Restart  the system to see the changes.

Wrong settings in the registry may cause an unpredictable problems to your Windows. So carefully change the appropriate values.