On boot, if you press Del (could be different on your comp) to enter the BIOS, and find the boot section, it will give you a choice of devices to boot first, (boot priority).
If you only have one HDD then make sure this is at the top, or make sure it is ticked, then press F10 to save and exit from BIOS.
It should reboot normally, if that fails then reboot and on the post screen select boot device or boot priority (could be F4 or F8 computer dependent) and this will take you to a blue screen with a list of devices attached to your mother board, and using the arrow keys select the HDD that your OS is on and press enter, it will reboot and should start normally.
Try not to mess with any other settings in the BIOS, this will only confuse matters.
And the best bit is its easy, and not scary, so dont worry about braking your computer
DT_Xtremez_30:
See if that works, if not let us know what it says or does.