I have this Aspire 5315 Laptop and it's giving my some crazy response on boot. The machine came with Vista on it but it locked me out and i attempted to reinstall Vista back on it but now it only shows the hdd in the bios and it won't post pass that. this is a picture it gives me. Also it will post in windows XP on my other machine.
Either the Hard drive is completely shot and you need to buy a new hard drive and do a COMPLETE FRESH install...... OR.... Your Motherboard is definitely dead and you need to replace it or buy a new laptop.