WinPE 2.1 missing windows operating system; operating system not found; unknown operating system

Article:TECH42754  |  Created: 2009-07-09  |  Updated: 2010-09-30  |  Article URL
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Technical Solution


When creating a WinPE 2.1 pre-boot using the PXE configuration Utility the process fails at the very end after the WAIK installer processes.

An error stating "operating system not found" or possibly "Unknown operating system" appears.

In the 'Altiris Boot Disk Creator - Install Pre-boot Operating System Files' the WinPE 2.1 Pre-boot OS shows as unknown in the status column, and there is no check mark to the left side.


DS 6.9 SP2


The cause is currently unknown but may be due to several or a combination of issues:

1: Microsoft's version of WAIK interfering with the Altiris WAIK included with WinPE 2.1. This may include Microsoft’s MDT08 (and Workbench)

2: The WAIK folder inside of the Deployment Server is corrupted and may, as a result, show 1 kb files inside.

3: The WinPE download is incomplete or corrupt. Check the current size of the download on the Altiris ftp site: (



Possible solution:

1: Remove any and all instances of Microsoft’s MDT08 (and Workbench) if they are installed. It is possible that the 2 versions of WAIK are interfering with each other.

2: Rename the existing WAIK folder inside the eXpress folder to WAIKold (or something).

3: Run the WinPE executable from the desktop to re-create the WAIK folder you renamed.

4: Restart the server.

After the restart you may see a window that says: "the WimFltr driver must be installed... Do you want to install the WimFltr driver". Select 'yes' and it should re-install correctly. At this point the WinPE 2.1 should be a selectable option inside the Altiris Boot Disk Creator window.

Other steps to try:

1: Re-download WinPE 2.1 from and try again.

2: Copy a the WinPE2 and WAIK folders from a working Deployment Server into the eXpress folder replacing the existing ones.

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