You probably have to do this in your BIOS, tell it to not boot from USB devices.

From an Intel site:

Resolving Slow Boot Times

Check the following tips to speed up the boot time of your computer.

Set the hard drive as the first boot device in the boot order in the BIOS setup (Boot > Boot Device Priority menu). Enable Intel® Rapid BIOS boot in the BIOS setup (Boot menu). Disable Hard Disk Pre-Delay in the BIOS Setup (Advanced > Drive Configuration menu). Disable system functions and features if you do not need them. Examples include: Legacy USB - this must be enabled if you use a USB keyboard or USB mouse outside the Windows* environment (Advanced > USB Configuration). Unused I/O ports, such as serial, parallel and IEEE-1394 ports (Advanced > Peripheral Configuration menu). Event logging (Advanced > Event Log Configuration menu). To enter BIOS Setup, press the key after the Power-On Self-Test (POST) memory test begins and before the operating system boot begins.

Warning: If any problems occur after making BIOS settings changes (poor performance, intermittent issues, etc.), reset the desktop board to default values:

During boot, enter the BIOS setup by pressing F2. Press F9 to set defaults. Press F10 to Save and Exit. If the system locks or won’t boot after making BIOS settings changes, perform a BIOS recovery as described at Instructions for Recovery BIOS Update.

You probably have to do this in your BIOS, tell it to not boot from USB devices.

From an Intel site:

Resolving Slow Boot Times

Check the following tips to speed up the boot time of your computer.

• Set the hard drive as the first boot device in the boot order in the BIOS setup (Boot > Boot Device Priority menu).
• Enable Intel® Rapid BIOS boot in the BIOS setup (Boot menu).
• Disable Hard Disk Pre-Delay in the BIOS Setup (Advanced > Drive Configuration menu).
• Disable system functions and features if you do not need them. Examples include: Legacy USB - this must be enabled if you use a USB keyboard or USB mouse outside the Windows* environment (Advanced > USB Configuration).
• Unused I/O ports, such as serial, parallel and IEEE-1394 ports (Advanced > Peripheral Configuration menu).
• Event logging (Advanced > Event Log Configuration menu).
• To enter BIOS Setup, press the key after the Power-On Self-Test (POST) memory test begins and before the operating system boot begins.

Warning: If any problems occur after making BIOS settings changes (poor performance, intermittent issues, etc.), reset the desktop board to default values:

During boot, enter the BIOS setup by pressing F2. Press F9 to set defaults. Press F10 to Save and Exit. If the system locks or won’t boot after making BIOS settings changes, perform a BIOS recovery as described at Instructions for Recovery BIOS Update.