WindowsBackend object has no attribute 'iso-path'

Did you MD5 test the .iso image before you wrote it to the USB flash drive? (See https://help.ubuntu.com/community/HowToMD5SUM.) If not, please do that now. If that doesn't check out, you'll have to redownload the .iso image, MD5 test the new image, and (assuming the new one checks out) write it to the USB flash drive again.

Did you verify that the live USB was written correctly and is readable by the machine on which you're installing? To do that, boot from it, and immediately when you see the person and keyboard icons at the bottom center of the screen, press Spacebar, select your language, and select "Check disc for defects". (This goes for USB flash drives as well as CD's and DVD's.) If that doesn't check out, you'll have to re-write the .iso image to the USB flash drive (and run this test on it again).

If both of those things check out, then you'll have to provide more information:

(1) What version of Ubuntu are you trying to install?

(2) What is the full and exact name of the .iso file you used to create the USB flash drive?

(3) What method, exactly, did you use to write the .iso image to the USB flash drive?

(4) What is the make and model of your computer (or, if it's custom built and that doesn't apply, then what is the make and model of the motherboard)?

By the way, if the installation reached the very end, then you might just be able to ignore that message. Ubuntu might have been successfully installed.

The USB is still install Ubuntu so I don't think it fully isntalled, if so how would I know?

1.) Im trying to install the newest version of Ubuntu.
2.) The full name is "ubuntu-11.10-desktop-i386"
3.) I used a program given on the installation page to write it to the USB drive
4.) My computer is a compaq presario P-something

"The USB is still install Ubuntu so I don't think it fully isntalled, if so how would I know?"

Click the power icon at the upper-right corner of the screen and click Shut Down. You will be asked if you really want to shut down. Click Restart. When your computer reboots, remove the USB flash drive, and see if a working Ubuntu 11.10 system boots up.

If not, then you should MD5SUM the .iso image and do "Check disc for defects" on the USB flash drive.

Your initial error message is a Wubi message. (Windows Ubuntu installer). You shouldn't install Wubi from a USB stick. Although it works in limited circumstances, in most cases, with modern large USB sticks it does not due to a simplistic ISO size check that is designed to prevent installing from a DVD image.

Wubi will copy the entire USB partition to the partition you choose to install on before rejecting it if the size is greater than 900 000 000 bytes.

That may also be the reason for the failure - the latest version of Wubi has some very unhelpful error messages so it's hard to tell unless you post the wubi install log. However, if you're now trying to install a normal dual boot (without Wubi) then just change the project from Wubi back to Ubuntu.

If you still want to install with Wubi, instead remove the USB, place wubi.exe and the downloaded ISO in the same directory and run from there. (If this fails, post the wubi log file from the %temp% directory to http://pastebin.ubuntu.com/ and the address back here)