I can confirm when having plugged in my iPod while booting. However, in my case I can only blame my BIOS since it happens twice. First before the grub menu, second after the grub menu, just before the kernel starts. As the kernel then doesn't have any problems (neither userspace), it seems (again in my case at least) the issue is really in the bios.
So, maybe you have the same thing going on. Otherwise, I'm afraid I can't really help w/o any more information.
P.S. Wow, my first post ..