Cannot uninstall corrupted ubuntu installation (Wubi installation)

I would suggest using Gparted to nuke it.

http://gparted.sourceforge.net/index.php

Hmmm, there's bad download links on Sourceforge. Download this .iso file (disk image) and burn it to a CD.

http://download.cnet.com/GParted-LiveCD/3000-2094_4-10698802.html

Put it in your computer and start it up. Just do a full reformat on your hard drive, or just reformat the specific partition of you have dual boot. Watch out if you have multiple hard drives on the computer and make sure you know what you are wiping out.

Good luck and ask questions!

If you have a corrupted WIndows OS, then using Wubi isn't very Wise. I suggest you boot to the install CD or USB (after MD5 testing the image) and install that way.

Gparted is also on the Ubuntu install CD, so there is no need to download an extra ISO as you already have the functionality.

Is there some reason you need to use the CD boot helper from Wubi, and can't just boot your computer from the CD itself? i.e. using BIOS boot options.

Restarting the computer with a CD in the drive doesn't automatically boot from the CD in question.

Here's the current boot priority order, as displayed via the BIOS:

1: Internal Optical Drive
2: USB Optical Drive (*)
3: Floppy Disk Drive (*)
4: USB Flash (*)
5: USB Hard Disk Drive (*)
6: Internal Hard Disk Drive
7: Network

Restarting with either the Ubuntu CD or the Gparted CD doesn't work correctly. It briefly displays a screen with a repeating sequence of open parentheses on it, before giving up and taking me to the "Windows Error Recovery" screen, on which I'm allowed to select from a series of restart options: Safe Mode, Safe Mode with Networking, Safe Mode with Command Prompt, Last Known Good Configuration (advanced), and Start Windows Normally.

Here are instructions to manually uninstall Wubi: https://wiki.ubuntu.com/WubiGuide#How_do_I_manually_uninstall_Wubi.3F
That should take care of that error.

There may be an issue with the CD if it's not booting via BIOS, in which case the Wubi CD boot helper won't work either.

One quick cosmetic change that occurred shortly after checking the BIOS: the area of the screen on which graphics are actually displayed has shrunk - the display now looks like it was the victim of an overzealous letterboxing process.

In any event, I believe I've successfully uninstalled ubuntu from my machine... although things are far from resolved. I've tried booting from the CD again, but the start-up process hangs on the screen with the repeating sequence of open parentheses.

Backing up, I've tried the "Help me boot from CD" option, but that still has some issues. The installer still detects an existing install, but reports that it has successfully uninstalled thereafter. The problem is that when subsequently attempting the install, it's stopped by the following error message:

"Ubuntu CD Boot Helper

An error occurred:

'WindowsBackend' object has no attribute 'cd_path'

For more information, please see the log file: c:\users\ianm\appdata\local\temp\wubi-11.10-rev241.log"

I've linked a bug that's related to this problem. I'm honestly not aware whether this always happens every time or not (or I would have said "don't bother" before). I don't think many people use this feature or it would have become clear beforehand.

Anyway... I think the answer to your problem lies in figuring out if a) you've got a good CD (which I suspect you don't) and b) if you can't boot from a CD, getting Ubuntu on a USB stick and booting from that instead.

Since I've been having trouble with booting from other discs as well as the ubuntu one, I thought I'd download a fresh copy, put it on a USB stick, and try installing it from there.

But that didn't work well either. The installation hangs on a long string of text, and the machine restarts.

Here's the final line of the text from the two different hangs I've been encountering:
When trying the "Run Ubuntu from this USB" option:
[( (<.377?96]([drm] nouveau 0000:01:00.0: 5: 0x88008;9;: iype(8x1;(idx =(tao(0xff (( (((( (( (( (( (( ((

and from the Install Ubuntu on a hard disk option:
[( (=.306:=6]([drm] nouveau 0000:01:00.0 VM: traxxed(^zite(it 8x0082b50=k on(ch 0 [0q0000058] BAR/TEXTURE/IN rmison:(XAGM_REIL_ONLY (( ((

I'm just about ready to give up on this entire project.

If you have a nvidia or some radeon graphics cards, you need to boot the
first time with 'nomodeset' and then install the driver for the card.
There's some sort of philosophical reason behind this that I'm not totally
understanding. Details are here:
http://ubuntuforums.org/showthread.php?t=1613132