Here goes, I had a dual boot system then I deinstalled Windows 7. I believe that Windows 7 leaves the boot loader so i ended up with.
Hard Drive 2: Bootable: Opening up the choise of OS between Windows 7 (even though Not installed hence my beliefe taht Win 7 leaves behind the boot loader). So on this screen I choose "earlier versions of windows and then it boots:
Hard Drive 1: Which has XP.
Since I wanted to clean this up I am trying a new install. Therefore I removed Hard Drive 2 and ran Win XP pro setup. Foolishly I believed someone who told me that there would be no problems. That XP would make HArd Drive one bootable and that then XP would install correctly.
I should perhaps note that I used a new copy of XP with service packs as I thought it would make more sense than the XP I've used previously which was the first version of XP.
Firstly, XP formatted the hard drive. Detected no problems. Then it copied across files. No Problem. Then on first loading XP I got the error message "Your BIOS" is not ACPI compliant. Contact Hardware Update.com to get update.
I have installed XP many many times on my system with exactly the same hardware and I have never got this message. Therefore I thought that maybe it was something to do with Windows 7 affecting the BIOS or maybe that XP with service packs conflicts with my motherboard. So I tried an earlier version of XP Pro that didn't have the service packs included.
Same message came up at the same time. On first running XP it gets to the Microsoft logo and then the same message comes up "BIOS not ACPI compliant."
At this point I thought that maybe the best thing would be to remove the CMOS battery. Clear the CMOS and therefore any bios setting would revert back to default and I could then proceed.
At this point when I rebooted the BIOS failed to detect the hard drive at all. I replaced it with another hard drive but still the BIOS doesn;t see a hard drive. I tried changing the SATA cables, changing which SATA port the drive connects too. I've now tested the hard drives in another PC and they are working.
So to recap:
BIOS doesn;t detect hard Drive.
Even when it did the XP installalation freezes at the fist run of XP saying BIOS not ACPI compliant.
As noted the hard drives worked before . I've reinstalled many times and never had any problems.
I am a total loss how to proceed. I've thought about flashing the BIOS with an update but since I've installed XP with exactly the same hard drive why should XP suddenly talk about ACPI. The BIOS not seeing a hard drive at all is weird. Even though I've changed SATA connectors on the hard drives and which connect to the Motherboard I'd expect it to see something.
Even though the BIOS doesn't show the HD doesn't mean that it isn't read. Try altering the way the SATA is read under the BIOS by switching between Native IDE and RAID if it gives you those options...just a suggestion
useful information which I'll no doubt try on next install. As it happens I (kind of ) solved the problem. I installed Media Center and it worked. Strangely it gave me a boot loader for different versions of windows but that may be because I tried (and failed) to install XP before getting the ACPI problem .
Here's what I think happened. I'm going to post this on the windows 7 part of the forum as I think it may be relevant for other people who try to change from 7 back to XP:
I set up Windows 7 on a virtual drive on my second hard drive.
I then installed W 7 from an iso image and ran W 7 from the virtual drive.
Since W7 was the release candidate and it had some problems I wanted to stick to XP.
So at this point I'm running a dual boot system
This is what I think caused the problem:
I had a boot loader which I think was Windows 7 boot loader. The (I think) W7 boot loader asks me if I want to load W7 or "earlier operating systems" So I then choose "earlier operating systems and the I choose my working XP version. (In fact I had two XP pro's running but only one would actually load.
So I chose the XP version I knew would load and then ran XP fine.
Now at this point I want to speculate on what caused all the problems.
Hard Drive 2 contained the W7 Boot loader. Hard Drive 2 is also the bootable drive so it has to go through HD2 before it can run the XP on Hard Drive One.
What I did was remove Hard Drive 2. Did a full format on Hard Drive 1 and then asked XP pro to install. All seemed fine, copied files across. However on the first boot up of XP, immediately after the Microsoft Logo I got a: "your bios does not support ACPI" message.
This is a pig of a message. What was some help was the fact that I'd installed exactly this hard drive and exactly the same hardware on at least half a dozen times. So something must have changed somewhere. Microsoft knowledge base was typically unhelpful. As wioth many problems it assumes that it the problem. In this case a Bios fix is the suggestion. However, any given Bios may not neecesarily solve the ACPI problem. You'd have thought that the latest Bios would be the one to go for but it seems taht with this particular problem that is not neccesarily the case. Sometimes it's better to choose an older Bios.
Looking in the Bios itself you can disable ACPI. Also pressing (I think) f5 at "install storage drivers" bypasses the ACPI routine and is supposed to in many cases solve the problem. However, pressing F5 (or F6 can't remember which one was suggested) doesn;t tell yhou that the Bios or the new operating system is bypassing it. According to micrososoft it happens even though you don;t get a confirmation message.
So reset the Bios back to default. Swapped hard drives, SATA cables. Formatted the hard drives with Sea Tools just in case the XP install was leaving bad files behind (Never quick format if you have to reinstall over a new install that goes wrong - when you reinstall again - on a quick format the "new" install sees the files on the hard drives and if the install went wrong the first time - the left behind bad files invariablty caused the same problem again.
All to no avail. Thought maybe my slipstreamed copy of XP pro with service Pack 3 was the problem so tried a bog standard XP pro. All to no avail. At this point the BIOS stopped seeing the hard drive altogether and I went to bed amid all the confusion.
So it seemed to me that there was some low level conversation between the operating system and the Bios and the PC. So I thought that maybe a different version of Xp would have a different conversation and maybe install over the problem or solve the issue.
So I tried XP Media Center and it all went fine. Oddlly when it loaded first time I had a dual boot loader witrh two versions of XP. Probably because I after so many attempts I was almost giving up and just before the last instal had a quick format rather than a full format.
However this is what I think caused all the problems:
Windows 7 has it's own boot loader. Now to those of use whove run dual OS setups under XP you just change the boot option in the boot.ini file and delete whichever option you don't want.
However and this is the point. I think that Windows 7 boot loader is much more than XP boot loader. When I failed at my install after deleting Windows 7 and the removing the second hard drive I think (and I do mean think) that the ACPI problem is caused by not removing windows 7 properly. I've alwasy thought that there were essentially two seperate things on an install the BIOS and the operating system. ACPI, if I understand correctly is concerned with with what's called the HAL or Hardware Abstraction Layer. This sits in between the BIOS and the OS. Now (again I believe) that Windows 7 alters the HAL. It communicates with the HAL on install and understand how it works.
When you simply delete Windows 7 you leave all the Windows 7 setting that work at this level and earlier operating systems have no idea how to communicate with the Bios OS and HAl properly. You can't (I believe) just format the hard drive and install an earlier operating system because there's information that the older XP can't understand or at least solve.
The lesson in all of this is never simply just delete windows 7 and think that an earlier operating system will install. I remember that you're advised to stick in Windows 7 and get windows 7 to clean up:
I'm posting this is the hope that other people benefit from my experience. I've seen other answers on forums where people suggest just deleting formatting and installing XP. Please don;t do it. I know it worked in the past but I really feel that not allowing windows 7 to remove itself caused all the problems. By the way it screwed with two hard drives. I tried to format the second hard drive but I couldn;t get anything form either hard drive. So I think Windows 7 can effect an hard drive that it's involved with. As I said even a format with sea tools failed to get the PC to see the hard drive and I think that I only succeeded with Media Center because it was slightly newer than XP.
In any case hope the above information is useful to someone and stops people going through the pain that I went through.