My parents' computer stopped booting from the HDD into Windows: it's showing a "Missing operating system" error. I tried burning a Live CD of the latest Ubuntu and booting from that, but it's giving me the same error. I know the Live CD works (I can boot my laptop from it). It does seem to be actually trying to boot from the CD (when I boot with the CD in it takes longer to get to the error message than if I boot with the CD out, or if I change the BIOS boot order to skip the CD drive; and the CD drive light is active during that time). Might this be a hardware problem? Are there common problems I can look for that might cause this?