Were you running the latest Nvidia patch
before your hard drive crashed? It
might be possible that newer drivers are the problem rather than the other way around. I've run into problems like this--especially with Vista... Have you installed any different programs before SH4? Windows updates all done? And I get a tech's "intuition" that DX10 may be causing some issues for people as well--though I can't prove it "yet".
In my experience--Vista seems to have a mind of it's own and does what it Wants to do regardless of what I Tell it to do. It's the only way I can explain the different behavior on identical hardware profiles that I've seen.
At least it's system restore "seems" to work
.
Just some ideas to think about.
Good Luck! Post more info as you get it. This forum has many knowledgable and helpfull people. Salute to you All!!!