Alright, guys. I'm working with a Gigabyte MA790XT-UD4P motherboard, Seagate hard drive (SATA), AMD Phenom II X4 CPU, and HP DVD burner (SATA). I've already got Vista installed on the hard drive (via another computer, so I know the hard drive works). However, if I try to boot the computer with both the DVD drive and hard drive plugged in, I get this message: BOOTMGR is missing Press CTRL + ALT + DEL It also won't let me boot from the DVD drive when I have them both plugged in. If I boot with just the DVD drive plugged in, it runs the disc. If I boot with just the hard drive plugged in, I get the same error message. I've tried using a different SATA cable and used every SATA slot available with the same results. I've quadruple-checked that the DVD drive is set to boot first, then the hard drive. BIOS recognizes the hard drive. I returned the motherboard for a replacement. No help. I've ordered a new power supply because the manual for the mobo suggested 500w or higher. No help. I haven't tried with a different hard drive yet simply because I don't have a spare one laying around and if the Seagate works when I stick it in my other computer, it should work with this new one. Please help!
your problem is, you didn't installed vista using the current motherboard. The setup of the computer you installed it in was different. Some of the startup files might have been installed in another drive. This is very complicated to fix. It might be easier to just reinstall vista, but this time on the motherboard it will be running on. below is a forum that deals only with vista boot problems, it might give you some ideas. http://www.pronetworks.org/forums/os-discussion-support-f235.html