Trying to install Windows 7 Ultimate (build 7600), I got the “Windows could not prepare the computer to boot into the next phase of installation” error message. I tried the installation once again, but the error kept appearing.

The problem was that I had deleted my old Windows XP, and though I had no operating system on the PC. Fortunately I did burn a copy of ” The Ultimate Boot CD 4 Windows” and it saved me a lot of time throught the process.

After searching for the possible solutions, I came to the conclusion that this error did appear regularly on Vista but as the Windows 7 is quite new, there where no clear documentation on how to resolve this problem.

Possible solutions are:

Disk Errors:

• Run a “CHKDSK X: /F” on your target disk (by replacing X with the proper drive letter)
• Format the installation target partition with tools like Ultimate Boot CD
• (WORKING SOLUTION FOR MY CASE) Using the Windows 7 installation wizard, firstly “DELETE” the installation target partition, then “CREATE A NEW” partition, and then with the same wizard, “FORMAT” the partition.

Unattend Setup:

• If you run an unattended setup, you might face the “Windows could not prepare the computer to boot into the next phase of installation” error message, and this is most probably because of improper partitioning information in the “unattend.xml” file.
• Check “Windows could not prepare the computer to boot into the next phase of installation” error on Microsoft knowledge base for details on this scenario.
• You can also try to remove the “unattend.xml” file and re-burn the source, to proceed with an attended install.

System incompatibility:

• To make sure that your hardware is not causing this error, I would recommend you remove all uneccessary connected devices, and keep only the strict minimum.
• Check for the minimum system requirements for Windows 7 on Microsoft’s ”Windows 7 minimum system requirements“

Installation Source:

It might be possible that the DVD you’re using for the installation be corrupt, so check it once, and if possible, get yourself another installation source.