try clicking on this link and choosing Master Boot Record Repair.
Also, have you tried
Step 1. Make the DVD drive the first startup device in the startup sequence using
the following procedures:
a. Shut down the operating system and turn off your computer.
b. Press and hold the F1 key, and then turn on the computer. When the logo
screen is displayed or if you hear repeating beeps, release the F1 key. The
Setup Utility program opens.
If the Setup Utility program does not open, shut down the
computer, wait approximately five seconds, turn on the computer, and
then immediately press and release the F1 key repeatedly until the Setup
Utility program opens.
c. Use the left and right arrow keys to select Startup
from the main menu.
From the Startup
menu, select Startup Sequence
and then press Enter
d. From the Startup Sequence [Primary]
menu, do one of the following to
select the DVD device that you want to use as the first boot device.
When selecting your DVD device as the first boot device, be aware
that internal DVD drives are listed as IDE CD. If you will be using a
supported external DVD drive as the first boot device, select USB
CDROM in the steps below for your choice of DVD device.
v If your choice of DVD device is already listed as the first boot device,
continue with step 2.
v If your choice of DVD device is listed in the startup sequence as any
device other than the first device, select it and press the Plus (+) key
repeatedly until it is displayed as the first boot device. Continue with
v If your choice of DVD device is listed as an excluded device, select it
and press the X key one time to add it to the startup sequence. Then,
select your choice of DVD device from the startup sequence and press
the Plus (+) key repeatedly until it is displayed as the first boot device.
Continue with step 2.
e. Press F10 to save and exit the Setup Utility. When the save and exit
message displays, select Yes
and then press Enter.