Hi there,
Sorry to hear about your troubles -- this is certainly an unusual one, and you've done a very thorough job already of trying to run it down. Whatever this issue is, from the looks of it it is below even the SlimDX level; my guess would be either driver trouble, something physically amiss with the GPU itself (overheating, etc), or an install of DirectX that is still somehow corrupt.
I'm running a very similar rig to you in a lot of respects: Q6600, 4GB Ram, Nvidia 8800GT, Windows 7 64 Ultimate. So it's certainly not a compatibility thing, of course. Looking at the drivers I'm using for NVidia, I see a driver data of 9/27/2009 with a version of 8.16.11.9107, which is working great. I think that is the 191.07 version, but I'm not 100% positive.
In the past I was running the 169.21 version, which was pretty out of date, but it was also working well. There were some reports of some bugs in the 180.x line that were causing some issues such as black screens, but that seemed to vary by the specific graphics card. I don't know if perhaps that is also the case for you.
Given your already thorough examination of your system, my best guess is that there is something bugged with those specific driver versions and your specific card. You might try going back to the NVidia archives a tad further to see if that resolves it, and that would at least pinpoint the problem -- and if that was the issue, then hopefully the next driver version will no longer contain whatever the issue is.
Usually when there is something wrong with Direct3D9 it either shows a black screen for the DX part of the game (bad drivers), or it crashes when trying to initialize Direct3D9 (bad/corrupt install of DirectX). You're passing the point of the initialization, but then it's failing when it is trying to flip the back buffer to the actual display, which is most unusual. Generally speaking, I'd expect most errors to occur before that point if it was a DirectX problem, so that's something that again leads me down the path to a bugged driver.
Hopefully that helps -- there are some others here with good technical backgrounds on strange DirectX issues, so they may weigh in with some thoughts on that as well. You might want to run some stress-testing on your GPU if this is still not working, just to make sure that that doesn't turn up any hardware faults. The fact that this is failing so quickly and immediately points to software to me, though, honestly -- if it was an overheating thing I'd expect it to fail frustratingly randomly after a varying amount of time.
