Keep in mind that Sandboxie does nothing to prevent sandboxed programs from reading any file on your computer that they wish (or at least that are readable by applications on your computer in general), it just restricts where they can *write* files. That means a program running under Sandboxie will be able to read your Bitcoin or Litecoin wallet.dat files all day long. As well as your web browser history, saved passwords, cookies, etc.. Calling it "sandboxed" may be providing a false sense of security..
The correct answer here is to run new coins in a VM (virtual machine) instead that is completely isolated from your PC. VirtualBox is free, if you have nothing better.
Actually you can specify to deny reading of files/folders in sandboxie. Settings/Resource Access/File Access/Blocked Access
http://www.sandboxie.com/index.php?ResourceAccessSettings#file