Daniel's PC says "boot device not found" when he turns it on. He checked all the cables and pulled the battery. That only worked once, though. Leo says that the battery is likely starting to fail and if that happens, it won't save the settings in the computer. Daniel should check the BIOS for the Enhanced System Configuration Data (ESCD) and reset it to default. Once that's done, reboot. After that, he may need to reinstall Windows.