what is "Other Operating System found" error

When you try to upgrade your Microsoft Windows 95-based, Microsoft Windows 98-based, or Microsoft Windows ME-based computer to Microsoft Windows XP, you may receive an error message that is similar to the following:

Error: Setup found some blocking issues.

Blocking issues Setup found some issues that will prevent you from upgrading your Windows Installation.

You must fix all of these issues before you can upgrade to Windows XP
"Other Operating System found"
The possibility for this errors are

* You previously installed Windows XP
* You uninstalled Windows XP
* Folders from the original Windows XP installation are still on your computer
there are several ways to resolve this issue

• Verify hardware compatibility

Verify that any external devices that are connected to your computer are compatible with Windows XP. Remove any external devices if those devices are not compatible with Windows XP.to check device compatibility with Windows XP
please visit http://www.microsoft.com/whdc/hcl/default.mspx

• Remove unknown devices that are listed in Device Manager.
• Delete previous system installation files
• Disable any antivirus software that is running on your computer
• Create a temporary storage folder for any files from the original system installation that are still on your hard disk.

Run Windows upgrade again.