Could you explain a bit more? Sorry.
As I understand it (well, what I think seems to be the behaviour of any sandbox) when I select a file from the right-click context menu in Windows, and run it sandboxed, Avast intercepts it, and and recreates neccessary environment for the program or installer to function, but the environment is within the sandbox and doesn't actually touch your system. So registry entries are recreated in a hive file within the sandbox, for example. The complexities of how it all works I don't even pretend to begin to understand, but it's the way I get my head around it. Anyhow, if I run an exe installer package sandboxed, as I did, and installed to program files for example, the installer would not be able to determine that it wasn't actually installing to ?\program files within the sandbox. So when I open the sandbox I find the replicated folder structure, and the installation folders and files inside..as long as the program or installer is running. As soon as I exit the installer or program the sandbox is cleared, except the root folder for that sandbox instance. This is how it worked when I tried it...very similar to Sandboxie. So why wouldn't .msi installers work the same way?