Warning
Wubi.exe not working
The wubi.exe available at
http://www.ubuntu.com/desktop/get-ubuntu/windows-installer is not working at the moment. Instead, for 10.10 Maverick Meerkat use
http://releases.ubuntu.com/maverick/wubi.exe or for 10.04 Lucid Lynx use
http://people.canonical.com/~evand/wubi/lucid/wubi-r191.exe.
You can also get wubi.exe by downloading the desktop CD ISO and burning it to CD - in this case the wubi.exe always matches the release you downloaded.
There is a critical issue on Wubi installs caused by allowing the Update Manager to update the grub-pc and/or grub-common packages.
Please avoid updating these packages on any Ubuntu Release until this notice is removed. If you have already run these updates and need help or would like more information, please see the Wubi Megathread on Ubuntu Forums
These problems can be avoided on a fresh install by locking the grub-pc and grub-common packages. See the main post (just after the Permanent Fix section) in the Wubi Megathread linked to above for more on how to do this.