This one has me scratching my head.

Turned on the computer and the bios tells me Bootmgr is missing. Ah! panic, looked in bios and one of my drives is not recognised which happens to be the O/S drive. I opened up the computer and re-seated the Sata connections and went back in to the bios - the drive is still not recognised, however, it's there in the boot order section as an IDE not Sata drive...A bit weird.

I select that drive as the first to boot and the O/S loads with out a glitch. My question is how can the O/S run if it's not recognised by the bios?