The DAZ install routine takes quite a long time on my machine to search and choose a Poser installation to load to. Other than that (several minutes), Stephanie loaded fine for me. It's possible a corrupted download would have caused you problems, and it's also possible your machine suffered some hiccup coincidentally. A normal install shouldn't kill your operating system, even if it gets interrupted. Did you try booting into safe mode afterward? An OS installation has to be pretty dead to actually require a format and reinstall. In the lack of light of further information, I'm tempted to say your computer company chose a route that was convenient for them, not you. I have several partitions on my hard drive, and there is nothing on the C: drive except Windows and a couple of programs that tie themselves into it too closely (Word, etc). If my OS dies, I don't lose any data. I strongly recommend that nobody keep data on their C: drive.