Cant install google chrome? It was installed but disappeared suddenly.

I had google chrome for a long time, then a few days ago i turn on my computer and it was completely gone. No trace of it. So I try to install it, and at the very last moment of a completed installation, it states there is a problem and must close. This has happened repeatedly. Any ideas?

Im using firefox now, which is pretty cool. The only thing I hate is that when i click the firefox icon to open the browser, it literally opens 20 seconds later. Is there some way to fix that? I like speed, and when i clicked Chrome and that thing just busted open, that was nice. If firefox can do the same, I`d be happy.