WhoCrashed cannot be always 100% sure about the drivers which are responsible for crashing your computer. Because all kernel modules run in the same address space, a kernel module is able to corrupt another. Also, a driver may be able to cause problems to another driver which runs in the same device stack. So keep in mind this software is not guaranteed to identify the culprit in every case but most often it does.
WhoCrashed relies on the Windows Debugging Package (WinDbg) from Microsoft. If this is not installed, WhoCrashed will download and extract this package automatically for you.