Hey all, I finally got this issue resolved and I wanted to go ahead and post on here so that if someone else has the same issues. After reloading drivers, reformatting the hard drive (due to an unrelated problem) and then reloading the drivers again, the same error continued until, at long last, the video card failed completely--it was, in the end, a hardware problem. Amnesia just happened to be using some of the card's features that triggered a crash before the rest of the card failed completely. The card was replaced and Amnesia now runs perfectly.
I also wanted to thank you guys at Frictional Games for all your help in troubleshooting the problem--unfortunately it ended up being something that neither of us were aware of, but thank you for your effort and patience.
I'm already loving Amnesia and I look forward to playing it in the weeks to come.