Comment 8 for bug 259540

I've tried several Ubuntu flavors (Gnome, KDE and XCFE, both x86 and AMD) both 9.04 and 9.10 on Windows 7 RC (Ultimate) ITA and Windows 7 Professional ENG and I always get the aforementioned error (without experiencing the fdisk warning):

   No root file system is defined.
   Please correct this from the partitioning menu.

I tried several combination of "Run as admin", compatibility mode and language to install (since someone said Wubi was able to complete installation with these parameters) but I had no luck...

I also tried to set up a straight dual boot configuration but I always get the same error message as above...

I've read somewhere (sorry, I didn't bookmarked the source) that it depends on some minor changes on NTFS made by Microsoft... I don't know if this is true, but I noticed that even if I told the Windows Installer to create only one partition, it created two partitions instead where the first is hidden and is 100 Mb in size more or less (it actually depends on the size of the disk) and the second is the actual partition I was expecting... The first partition is used to store system file in case you need to recover the system in case of failure (on former versions of Windows you were supposed to use the Windows DVD instead)...
This is what you get by default unless you are installing on a disk with several already existing partitions or you bypass the standard procedure and you take control of the process...

So I came up with this idea: is the target partition hardcoded in Wubi?
I mean, is Wubi always trying to install Ubuntu on disk 0, partition 0, etc. by default?
If this is true and you have the hidden partition on your machine, then the Ubuntu installer called in second step by Wubi after reboot fails because it's performing its job on a partition different than the one expected...

I hope this helps, since I really need to install Ubuntu... In case my explanation was not clear enough (very likely) I can provide further details...

Thanks in advance,
     Stefano