I'm on a laptop, not really the best but I've managed to play through the game smoothly graphics wise.
Some of my laptop specs:
Processor: Intel(R) Core(TM) i5 CPU M 450 @ 2.40GHz (4 CPUs), ~2.4GHz
Memory: 4096MB RAM
DirectX Version: DirectX 11
Card name: ATI Mobility Radeon HD 5000 Series
Manufacturer: Advanced Micro Devices, Inc.
Chip type: AMD Radeon Graphics Processor (0x68C1)
EDIT: I've tried killing off the boss again, I've found if I die and I press Enter to reload the last save It crashes as well.