Whats d+??
d+ means defence+, which make Comodo leakproof. This is not the firewall part but the HIPS part.
I suggest you to use v4 because it is simpler to use and faster too. Sandbox will not bother you if you don't use. Leave it unused. I don't think there was a option to not install it...
It is a cool feature though. Let me make this clear to you. Suppose somebody sent you an unknown executable to you. You scanned it with your antivirus and find nothing. You can't be sure because new viruses are emerging time to time and no AV is perfect. Now right click on the file and select 'run in comodo sandbox' and see what happens. If something weired happen and you will be confirmed that it is a virus then also no headache as you ran that in virtual environment. But if you find this as legitimate, next time run it normally. That's the use of sandbox.
