The only version that I can get to be stable is the OpenGL 64-bit version, but I get a maximum of 20 FPS in that version. I believe my problem earlier was that I was mistakenly launching the 32-bit version via Steam.
I would love to use the 64-bit DirectX version because it runs way better (~90 fps vs 20 fps), but it crashes immediately when I go to file>save (or save as). Any ideas as to what might be wrong?
Also, thank you for your suggestions. I've ensured Windows is up-to-date and I've tried launching 3D Coat as an administrator, but neither has an affect.