Just wanted to follow up, as I *may* have found the culprit.
After MUCH troubleshooting, it seems the problem was isolated to exclusive access mode. Turns out that, even though I wasn't utilizing it, the problem lied in the Realtek drivers for my onboard sound card. I have an application that doesn't play nice with USB sound cards for some reason, and that was the only thing I kept the onboard card active for. However, because I wasn't playing audio through the onboard sound when I was experiencing the memory leak, it was like looking for a needle in a haystack.
Uninstalled the Realtek drivers, and on reboot, the Microsoft drivers were automatically installed. The memory leak hasn't occurred with the MS drivers (yet), but to test, I reinstalled the Realtek drivers and the memory leak returned.
Although more limited in functionality, I don't need the additional features of the Realtek onboard card, since the nitpicky app only needs basic stereo output.
Edit: Nope... problem still persists. It's not isolated to MC, but any app trying to use exclusive access of *any* sound card installed on the system.