Could be a disk that has been swapped into your machine and therefore Windows will not start with your motherboard. Any more details? Can you press delete or F2 to get into the BIOS and then see which drives are detected? Which version of Windows?
I can see the and get to the BIOS, but not able to tell what version of windows, and not sure if i know how or if it is just not available for me to see.
What other kind of details would be helpful to give you ideas on what is wrong, I'm a hack, that probably knows just enough to think i know something and thats the worst kind...