In Advanced BIOS Features make sure the hard drive is the first boot device. Then 2nd is DVD & 3rd is floppy.
In Integrated Peripherals you can disabled this:
USB Storage Function
Determines whether to detect USB storage devices, including USB flash drives and USB hard drives
during the POST. (Default: Enabled)
In the bios under Standard Cmos Features you can turn off the Halt on Error
Halt On
Allows you to determine whether the system will stop for an error during the POST.
All Errors Whenever the BIOS detects a non-fatal error the system boot will stop.
No Errors The system boot will not stop for any error.
All, But Keyboard The system boot will not stop for a keyboard error but stop for all other errors.
(Default)
All, But Diskette The system boot will not stop for a floppy disk drive error but stop for all other
errors.
All, But Disk/Key The system boot will not stop for a keyboard or a floppy disk drive error but it
will stop for all other errors.