Sometimes, the auto load sequence runs in a different order from the Step-by-step sequence (although not always and its hard to find out). it would seem to me that when you load step-by-step yu are loading them in a different order, therefore bypassing the problem that hits the PC during autostart up.

You can however set the order in which the auto start loads the drivers. So if you took notes of the order that the step by step way loads them, then configure the auto-start to load them in the same order it should (in theory) give you the same result (all drivers loaded)

It can take a while to configure the autostart sequence at first, but it is worth it. Im not sure if the version you are using is compliant however, but if you check this link it might help??

MSDN Whitepapers