everynowbot

Alrighty, we had the exact same problem: After installing Windows 7 Professional 64-bit, upon reboot (without the install disk in the drive), we would get the 'missing or corrupt system32ntoskrnl.exe' and couldn't startup. All the same, the computer would startup windows 7 without a hitch when the install disk was in the drive.
After running the disk repair console many times, and trying to fix the boot.ini file many times, and actually doing a fresh install many times, what ended up fixing the problem:
-disconnect all usb hardware from the computer except the mouse and keyboard.
-disconnect all extra hard drives that you may have so that the ONLY hard drive in your computer is the one the OS is being installed on (this is what we suspect fixed the issue)
-we also took all the RAM chips out except one, leaving the computer with 2 GB RAM (this was a precaution, and we don't suspect that this is what fixed the problem)
Boot the install disk and perform a clean install of Windows 7.
After the first startup, reboot the computer without the install disk in the drive.
Once we confirmed that the computer was booting without the install disk no problem, we did the following:
1. Reinstalled RAM and all usb peripherals and booted it up (worked)
2. Reinstalled one secondary hard drive and booted it up (worked)
3. Reinstalled last and final hard drive and booted it up (worked)
This is what solved the startup 'missing or corrupt system32ntoskrnl.exe' error for us after trying every other method on the forums.
Hope this helps!