no root file system is defined

Have you tried mounting the desired partition to "/" (as root) in the advanced partitioning options during install?

You might be better off on the Ubuntu forums next time for such questions, though.

Hope this has been of help.

This problem can be caused by:
1. Minor MBR partition table corruption (not enough to bother Windows but Ubuntu doesn't like it)
2. An unsupported fakeraid setup e.g. Raid 0 or Raid 10 (or fakeraid metadata but no raid in place)
3. A mix of GPT and MBR partition table data e.g. if a drive was previously used on a Mac

The best way to figure this out is to run the bootinfoscript: http://bootinfoscript.sourceforge.net/ and post the results to http://pastebin.ubuntu.com/ (and the pastebin address back here).

If you can't boot an Ubuntu CD or USB in "try it" mode to run the bootinfoscript, you can reinstall with Wubi and when you get the error drop to a terminal Ctrl+Alt+F2 and enter:
sudo parted -l (that's a lower case -L)

If there is partition table corruption the above command will spit out an error.

Running:
sudo fdisk -l (again lower case -L)

If you have GPT partition table data it will warn you.

Running:
sudo blkid

Should tell you if it detects a raid.

Hope that helps

Thank you i ll try these