I heard about this on Download Squad…
The nightmare scenario: your computer won’t boot. The drive seems healthy otherwise; you can access it when booting from another drive, but for some reason your drive absolutely refuses to boot. Take heart, it’s possible that it can be fixed by TestDisk, a very powerful cross-platform partition recovery tool.
I haven’t tried it yet, but I wanted to pass the information along. You can read more about on the Download Squad site or on the CG Security site.
Note: CG Security is the maker of the PhotoRec software that Chris mentioned last summer.