Unable to install ubuntu 12.10 on a pc with ubuntu 10.10 installed

See https://help.ubuntu.com/12.04/serverguide/installing-upgrading.html

Did you MD5 test the ISO you downloaded?
Did you burn the CD as slowly as possible?
Did you NOT extract the ISO file and burn the file as it was downloaded?
Did you NOT use the Windows inbuilt CD burner?

Thanks

Please also make sure to change the boot order in the BIOS so that the PC first tries to boot from CD-ROM instead of the harddisk.

Please also follow the other suggestions as well.

How have you created the boot disk?

1. You should first check the quality of the download for errors : MD5 check See here for how
https://help.ubuntu.com/community/HowToMD5SUM

2. Burn your CD/DVD as slowly as possible. Note you are burning an image not just copying the files and you will need an 800MB CD or DVD as 12.04 does not fit on a standard CD.

3. Go into your BIOS settings and make sure the CD/DVD is set to boot before the hard drive.
Note: there is usually some key to press at start-up to get into these settings. It varies my manufacturer but you should be able to find it easily by Googling "BIOS settings <computer make> computer"

If this does not work for you let us know what errors you get.

Thanks pasche, that solved my question.

Hi, I am a newbee when it comes to using (or attempting to install) Ubuntu.
I started working on computers in 1982 so I have been through the gamut of msdos and every version of windows except 2000.
Borne out of the frustration of windows 10, I decided three days ago to try to learn Linux. I decided initially to run the program on a partition which also had windows 10 in a computer containing windows 7 (on a separate hard disk) and a separate internal backup hard disk. I also have an external hard disk for backups which is connected via a usb3 port. I thought I was well protected against failure loss of data and multiple backups.
Through my experience I had printed out all installation notes for Ubuntu version 16.04. LTS 64 Bit also the article on dual booting with windows
I produced an iso image for both 32 bit and 64 bit Ubuntu. I am very familiar with this procedure having done it many times in windows and earlier in msdos. I verified both disks.
Initially I tried installing the 64 bit version as I have that type of system. My first problem occurred when I lost both my windows 7 and windows 10 boot-loader and I was unable to start either program. My backups also were corrupted and again I had to repair the MBR to make them useable. I re-installed windows 7 and windows 10 from backups. Please note that I have windows 10 on my system as I have been on the windows 10 insider program for over a year. I decided after the repair that I would do no more work with Linux on my desktop due to the disastrous initial use of Ubuntu.
I have a Laptop with windows 7 and I decided to add a 500gb external hard drive connected via a usb3 port in which I would install Ubuntu. further problems developed when the install was taking place. Ubuntu was almost fully installed but fails every time it tries to install the GRUB program. The laptop locks up at this point and I am only able to reset to the windows 7 operating system with ctrl-alt-delete. I have tried to install the 32 bit version with the same result.
Can you help as I am almost there with the install.

One thing that I forgot to add is that my windows 7 is installed on an ssd within my Laptop. I am assuming Ubuntu recognises ssds.
I upgraded my Laptop about a year ago with a ssd, 8gb of memory, a fater processor and I installed a cd/dvd writer. My Laptop is a Lenovo Thinkpad R500 built in 2009. It runs extremely well after the upgrade. I also built the desktop computer in 2009 and I have upgraded it as required.

@Randall: do not hijack this "solved" thread, but create your own question at the following location:

https://answers.launchpad.net/ubuntu/+source/ubiquity/+addquestion

Thank you for your understanding.