Having usb devices plugged in shouldn't affect the boot process. But something is stopping you from entering the bios. I thought I had figured out a possibility, that the keyboard was malfunctioning, but it looks like that isn't what is going on.

From what I've seen, the computer isn't even getting to the point where it looks for the operating system. And if you can't get into the bios, this could be a problem. Clearing cmos is the first step...whenever you want to try that.

After that I would try accessing the bios again---hitting Del as you boot up. See what is recognized in the bios and make sure the boot order is set correctly. If you can even get into the bios.

But lets take this one step at a time. Whenever you have a fair amount of time to work with this.

As far as helping, eh, that's what we do around here. Keeps us out of trouble.