Try pulling the CMOS battery out for ~5 minutes, then put it back in. It'll look like a silver watch battery on your motherboard.
Just a quick add on, last time i did this, it reset all of the BIOS information including the clock and date, you might want to reset them to their proper dates and times
OH, and dont forget to unplug the system and drain the power supply before doing any work on the motherboard.
Did you recently flash the BIOS? After doing so, sometimes it takes a while for the OS to boot. Do you have a CD in the driver, or any other removable media plugged in, like a thumb/USB drive? It could be something to do with the boot order.