Unplug all other HD's and peripherals, Boot into BIOS setup to see if there is an EFI Boot Disk in BIOS Boot order. If so remove it, set DVD drive first to boot. If EFI BIOS also set to Legacy BIOS.
Then boot into installer DVD or flash stick, at first screen Press Shift + F10 to open a Command Box, type:
SEL DIS 0 (after confirming Windows 7 target HD #)
CREATE PARTITION PRIMARY SIZE=102400
FORMAT FS=NTFS LABEL="WINDOWS 7"
Next click Install Now to Clean Install Windows 7
to partition you created. If it fails then report back at which step and the verbatim error message.
In addition read over these steps to understand the tools and methods which work best to get and maintain a perfect Clean Reinstall - Factory OEM Windows 7.
The steps are the same for retail.
Where did you get Windows 7 installer? DId you burn it yourself? Try another using ImgBurn at 4x speed, after confirming the ISO from Step 1 of tutorial above.