First of all, yes memory corruption will still bring the whole thing down. Only pure micro-kernels can survive it.

What Windows does, is that there aren't any direct calls between modules, only kernel level RPC calls.

All parameters are packed into the RPC message, it is dispatched, unpacked, validated as much as possible on the receiving end, then processed.

Messages and its validation introduce an indirection layer that improves safety.

It is based on the original micro-kernel design Windows NT had, before they moved graphics back into the kernel.

So the micro-kernel message passing is still there, but simplified since now everything runs on the same space. But as of Windows Vista, UDF was introduced for user space drivers.

The "Inside Windows" book series go into great detail how everything works.