This works for most people and is the advice I usually give to Mac users that are having mysterious installer failures. We have enough of a population that everything that can go wrong will. Disk corruption is one of those inevitable things that happens, and it causes mysterious problems. The installer isn't doing anything complex -- it's basically a glorified unzip tool, so when simple operations like "write a couple files" fail, it's typically that we're making a completely standard call the operating system that should never fail, and it's failing -- either silently or with an error, just depending on what's going on.
For what it's worth, I actually correctly diagnosed a broken pin on a monitor cable today based on the description some funky intermittent video playback behavior, so we really *do* see everything on these forums.