You cannot select the Upgrade option when you try to install Windows Vista, and you receive the following message: “Windows cannot determine if another operating system exists on your computer”


When you try to install Windows Vista, you cannot select the Upgrade option. Also, receive the following error message in the Install Windows dialog box:

Upgrade has been disabled

- Windows cannot determine if another operating system exists on your computer. Try repairing the boot configuration, and then begin the installation again.


This problem occurs if the Boot.ini file contains incorrect entries. Specifically, this problem occurs if the boot path in the Boot.ini file does not have the correct location for the Windows directory.


To resolve this problem, edit the Boot.ini file to correct the entries that are not valid. For more information about how to edit the Boot.ini file, click the following article number to view the article in the Microsoft Knowledge Base:

289022 How to edit the Boot.ini file in Windows XP

More Information

The following is a sample of a default Boot.ini file on a computer that is running Microsoft Windows XP Professional. The following example shows a single-partition integrated device electronics (IDE) drive that has Windows XP installed in the Windows folder:
[boot loader]
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /NoExecute=OptIn

Article ID: 927295 - Last Review: Oct 22, 2008 - Revision: 1