As everyone, I downloaded the Windows 8 Developer Preview to start playing with what it looks like a big step forward from Microsoft.

I downloaded the Windows 7 USB/DVD Download tool to create a bootable USB pendrive and it failed with the error message “Unable to copy files…”

I used this very same pendrive to install Ubuntu, so I guess that, even though I formatted the disk, something was still there, on the boot sector or MBR.

I found the solution in this article:

Run "diskpart" from a command prompt with admin rights
list disk
select disk # (the number of your USB)
clean
create partition primary
select partition 1
active
format quick fs=fat32
assign

Run again the tool, it will work without problems now.