Ok so I have two hard drives, one is SATA 500gb and the other is IDE 150gb. I had Windows 7 on the SATA and an old Ubuntu on the IDE hard drive. I hardly ever used Ubuntu and got tired of GRUB coming up every time I booted asking which OS I want so I decided to uninstall it. I wanted to go ahead and reformat the drive so I used an old Windows XP cd I have to reformat the 150g IDE drive. It wouldn't let me just reformat without installing XP so I went ahead and did that...
So now whenever I turn on the PC it automatically boots into Windows XP. In XP I can see both drives, my 500gb with all my files and Windows 7 and the 150gb with just XP on it. In my BIOS the SATA 500gb is set as the main hdd, and is set as #1 in the boot priority (IDE hdd is not anywhere in boot priority). When I bring up the boot list and choose the SATA HDD it just brings up a BIOS flasher, no Windows 7.
If I just unplug the IDE 150gb HDD, I get a Windows error when I try to boot.
What's going on? The Windows 7 installation isn't corrupt as far as I can tell, it worked this morning when I still had Ubuntu/GRUB on the other hdd.
Also when I put in my Windows 7 DVD and boot from that, it loads files then comes to the blue windows 7 background screen and the mouse cursor shows loading for a few seconds then stops and nothing happens...The DVD looks completely scratch free and has worked before.
Edit: the exact message I get when trying to boot to my SATA 500gb HDD is:
"Windows could not start because of a computer disk hardware configuration problem. Could not read from the selected boot disk. Check booth path and disk hardware. Please check the Windows documentation about hardware disk configuration and yo ur hardware reference manuals for additional information."
it sounds like your computer is upset that you removed Ubuntu. you should reinstall i after Windows 7. So first of all make sure both hard disks are plugged in and seen by the bios. the 500G drive should be in SATA 0 and the smaller 150G drive in SATA1. Now boot off the windows7 disc and install it to the 500G drive. once that is completed you can then install Ubuntu to the 150G drive. Yes it will have the grub bootloader again but you can change the default OS and the timeout if you want to have one. Good luck.
What you should have done was to reformat the small drive from within disk manager on W7. At this point I think you will have to reinstall W7 after unplugging the small drive. Then you can do what you should have done in the first place.