"Unknown hard error" and unable to boot windows

[Cuchulain]

Hi folks, my PC bluescreened this morning with an "Unknown Hard Error", I powered it off and it just sat at "loading operating system" (you can't even get into safe mode at this point).

I went into the BIOS and reset the Sata controllers to use IDE instead of AHCI and it booted ok, trouble is, I want to use AHCI, it's been fine for weeks using it so I'm mystified as to why it suddenly won't let me. Nothing has been installed/uninstalled recently, not even windows updates, no hardware has been added or removed etc, any ideas what it might be?

Cheers.

 

[Cuchulain]

even with IDE it's ended up bluescreening now. However, bootrec /fixmbr from a recovery console has fixed it and I'm back on AHCI, I can tell you're all very pleased for me

 

[d_brennen]

Get some hard disk diagnosis on the go, chkdsk and hdtune. Also pull any Ata that you value in case it's a sign of things to come!