I tried installing Ubuntu 10.04 and I got this message - any ideas on what to do?

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

This message shows up when I first boot into Ubuntu after the installation.

I installed it by mounting the ISO with Daemon Tools, and I just did the default Wubi installation. I keep reading everywhere that I need to choose my installation directory, but I don't get any option to do that. These are all the options I get for installation directory:

I have a C and D partition on my drive, and I tried installing it on both and no luck either way.

Any ideas?

Looks like there is a problem mounting the root file system. We'll need more info to fix you up, like motherboard or SATA chipset information.

When you see the bootloader screen, press ESC and select "Verbose Mode." When the error appears, press CTRL+ALT+F2 and run:

sudo sh /custom-installation/hooks/failure-command.sh

You can now reboot into Windows, the logs should be in C:\ubuntu\installation-logs.zip

Have a look at the logs and see if you can find the cause.

Reference: https://wiki.edubuntu.org/WubiGuide