Do you by any chance have some external USB drive plugged in? Sometimes, when you get such error, it is due to the fact that the motherboard Bios is trying to be smart and will attempt to boot from drive other than the internal drive. If that happens and the external drive (this includes Thumb Drives) will be used as boot drive.
In addition, if the above is not the case, few things you should do: Clear the CMOS on the motherboard, but to do that, you will need to know how. Check the drive in question for integrity which will have to be done outside of the Windows enviroment. This integrity check should also include test MBR (Master Boot Record)