Win XP stopped booting. What happened?

I have used Win XP Pro SP3 with a computer built on MSI Z87-G43 mobo.
Recently and suddenly it stopped booting showing an error message
"Reboot and Select proper Boot device or Insert Boot Media in selected
Boot device and press a key"
If I start with XP installation CD, it crashes before Windows starts.
Strange thing is that if I use a Windows 7-installed harddrive, it boots
normally.
I imagine that the BIOS has somehow changed to accommodate Win 7,
perhaps from native BIOS to UEFI. I see in Boot Mode selected
"LEGACY+UEFI". (Other choice is "UEFI" only.)
I cannot remember if I used this computer to test Win 7 in the past.

Can somebody tell me what happened to this computer? And how can I
restore the system so that I can continue to use Win XP?
JT

On 03/06/2016 02:31 PM, JT wrote:
I have used Win XP Pro SP3 with a computer built on MSI Z87-G43 mobo.
Recently and suddenly it stopped booting showing an error message
"Reboot and Select proper Boot device or Insert Boot Media in selected
Boot device and press a key"
If I start with XP installation CD, it crashes before Windows starts.
Strange thing is that if I use a Windows 7-installed harddrive, it boots
normally.
I imagine that the BIOS has somehow changed to accommodate Win 7,
perhaps from native BIOS to UEFI. I see in Boot Mode selected
"LEGACY+UEFI". (Other choice is "UEFI" only.)
I cannot remember if I used this computer to test Win 7 in the past.

Can somebody tell me what happened to this computer? And how can I
restore the system so that I can continue to use Win XP?
JT



More the likely the harddrive has failed

JT wrote:
I have used Win XP Pro SP3 with a computer built on MSI Z87-G43 mobo.
Recently and suddenly it stopped booting showing an error message
"Reboot and Select proper Boot device or Insert Boot Media in selected
Boot device and press a key"
If I start with XP installation CD, it crashes before Windows starts.
Strange thing is that if I use a Windows 7-installed harddrive, it boots
normally.
I imagine that the BIOS has somehow changed to accommodate Win 7,
perhaps from native BIOS to UEFI. I see in Boot Mode selected
"LEGACY+UEFI". (Other choice is "UEFI" only.)
I cannot remember if I used this computer to test Win 7 in the past.

Can somebody tell me what happened to this computer? And how can I
restore the system so that I can continue to use Win XP?
JT

A UEFI BIOS can have CSM. That's what "Legacy+UEFI" means.
The CSM provides the traditional BIOS services, so an older
OS can boot.

The second variable, is the operating mode of the SATA or
IDE cables. When the OS was installed, some disk mode
was set in the BIOS. For example, WinXP has IDE mode drivers,
but not AHCI. Whereas Win7 has both. And Win7 has a "rearm capability",
so you can switch from IDE to AHCI or vice versa. To save time,
the Win7 set of drivers doesn't "sniff" the setup each time
it starts, to save time. When you set certain registry settings
to rearm driver detection, Win7 can try its MSAHCI driver or the
IDE driver, and use the one that works. Then that choice is
remembered for the next boot.

WinXP doesn't have that feature. And in some cases, retrofitting
a driver change like that, is quite challenging (a lot of messing
around).

The mode of the disk ports, gets reset if the CMOS battery fails
and you've left the computer unplugged for three years. That'll
change the choice.

A second way, is for a "crash" to trigger a recovery procedure that
includes removing any overclock (stock multiplier and BCLK choice),
but may also include setting the disk choice. And on a newer motherboard,
one intended for easy usage with Win7, the default might be AHCI.
My laptop defaults to AHCI.

So since WinXP isn't all that flexible, the idea is to get
WinXP working, then go back and get Win7 working again. That's
the basic method.

On my new machine, I put a WinXP OS on it for a few days, just
to test how much faster my RAMDisk would be on WinXP. And I
was flipping the BIOS back and forth between IDE and AHCI. And
if you're not careful, you can forget to flip it again,
then you get a BSOD like a 0x7B.

http://aumha.org/a/stop.htm

0x0000007B: INACCESSIBLE_BOOT_DEVICE

HTH,
Paul