Figured it out through a strangled route. I was having trouble with my Lync client for work, which was crashing every time I started it, and I contacted help desk (gotta love BYOD, I get tech support for my personal computer). They had me reset the defaults on my speaker/headphone settings, which had apparently been corrupted somehow. That fixed Lync, and it turns out it fixed SC4 as well! Now when I get into the game, about 5 seconds in the music starts playing! That's what was causing the crash! Hooray for business tech support fixing my game