LostCub

I was told (I suspect incorrectly) to increment the Version of my setup
project every time I build a new MSI or the MSI won't install.

When I do that it tells me to change the ProductCode property of the project
which I suspect is a bad thing but I don't know any better so I do it anyway.

I guess the question is: when should I increment the version of my setup
project? And when I do should I change the ProductCode?