Update:
Just came back from vacation and decided to idiot-test the issue. I copied the text of my program into a new VS2010 project and set the project include and dependencies afresh. The only change I made this time was depositing my sound and texture files into their own folders, along with a number of text files, and map arrays, and deleting about half a thousand random files that look like VS logs of some kind.
The issue has disappeared for now, thankfully, as I quite like SFML. I was able to encapsulate the buffer and sound objects into a bundle, initialize them as a unit, and play the sound. (Does this seem like a reasonable way to handle sound effects that I don't want multiples of, assuming I need less than 256 individual sounds?)
I can't for the life of me figure out what the issue is, but apparently it wasn't the architecture. I'm... basically going to shrug it off and move on, unless anyone needs further reporting on the issue for whatever reason.