Now modify its value by double clicking it and set it to 3FFFFFF (Hexadecimal) .
Restart your computer. So, now when you click on My Computer, no drives will be seen.
To enable display of drives in My Computer, simply delete that DWORD item NoDrives that you created (it can be deleted by navigating to HKEY_CURRENT_USERSoftware MicrosoftWindowsCurrentVersionPoliciesExplorer and selecting the NoDrives and deleting it..del key...).
Again restart your computer.
You can now see all the drives again.