USB
I notice sometimes a computer won’t start up when USB printers, drives, or any other USB hardware is plugged in and turned on, so if your computer suddenly pauses during start up. It is worth it to turn off your printer, external USB drives, Scanners, webcam, tablets, etc. I’m not sure about firewire causing pauses during start up, but it is probably possible. I never owned any firewire devices, so I have not tested this out .
If you are using a laptop, and it freezes during boot up, try taking out your PC cards in your PC card slot.
USB, Firewire, E-sata, Laptop PC cards are all hot-swappable which means you can remove and insert them when the PC is on unlike serial ports.
All you need to plug in during computer start up is ypur key board, mouse, monitor, power, and network. It is okay to unplug all your other devices.
You can try flashing your motherboard BIOS to the latest version to fix this problem, but flashing your BIOS can be risky since if you lose power, or your computer freezes, your motherboard BIOS will be corrupted, and your PC won’t turn on unless your Motherboard has a backup bios.