Can't install or boot: (initramfs) mount mounting /dev/loop0 on filesystem.squashfs failed: Input/Output error

May be your Ubuntu live install cd is not perfect or it can't be read from your cdrom drive please verify it...

Here some general note on install Ubuntu and howto to get a good ubuntu iso cd image (.iso) to burn on a cd:
(some examples and videos links refers to Ubuntu 10.04.1 but the install stepa are similar for Ubuntu 10.10)

- Here the steps to install Ubuntu 10.04.1 https://help.ubuntu.com/community/GraphicalInstall

- Here install Ubuntu video http://www.youtube.com/watch?v=XaqaDZZ_P0g&feature=fvw
(The example used in the video is Ubuntu 10.04.1. The process may be similar for other versions.)

Below there are some intructions to:
--- 1) Ubuntu prerequisites... and Ubuntu for pc with low power
--- 2) download the iso...
--- 3) check the md5sum of the iso image, please don't forget to check...
--- 4) burn the iso image to a cd ...
--- 5) install Ubuntu using the self made cd ...
--- 6) trouble screen at installation or at first boot after installation ...
--- 7) Ubuntu manual and online help...
--- 8) Relax and fun...

The main ubuntu site is this: www.ubuntu.com and the download location is this
http://www.ubuntu.com/desktop/get-ubuntu/download

--- 1) Ubuntu prerequisites: https://help.ubuntu.com/community/Installation/SystemRequirements

Ubuntu 10.04.1 release notes: https://wiki.ubuntu.com/MaverickMeerkat/ReleaseNotes

If your ram is less than the recommended amount, you won't be able to install with the graphical installer,
but you might be able to use the Alternative cd, where you can use a text based installer - that uses less memory.
If your machine does have plenty of ram, you might want to try running Memcheck (which is also an option from the live cd, see below)
to just make sure your ram isn't failing.

- if your pc doesn't meet the Ubuntu prerequisites, you can try:

xubuntu http://www.xubuntu.org/get
lubuntu http://lubuntu.net/blog/lubuntu-1010-released

here a list from distrowatch: http://distrowatch.com/search.php?category=Old%20computers

- if you pc is a very low resource pc you can try different Linux distribution something like:
 Slitaz http://www.slitaz.org/ : Slitaz 3.0 release note http://www.slitaz.org/en/doc/releases/3.0/relnotes.en.html
 DSL http://www.damnsmalllinux.org/
 Puppy Linux http://www.puppylinux.org/

1.a) Please always prefer to download them using torrent if you can...

1.b) BE ABSOLUTELY SURE to verify the md5sum https://help.ubuntu.com/community/HowToMD5SUM
of the downloaded iso image BEFORE to burn it

1.c) burn it using infrarecorder http://infrarecorder.org/ if you are using Windows at lower speed you can do

1.d) boot your pc from cd and install...

--- 2) please download the 700 mb file http://www.ubuntu.com/desktop/get-ubuntu/download simply press on download button
To avoid download errors download the desired ubuntu iso install cd image using the torrent protocol.

- if you are using Windows please install a torrent client i suggest you http://deluge-torrent.org/
and download the iso using a .torrent link from here:
http://releases.ubuntu.com/10.10/ubuntu-10.10-desktop-i386.iso.torrent

--- 3) PLEASE BE SURE TO CHECK the md5sum of downloaded file to be sure it have no error https://help.ubuntu.com/community/HowToMD5SUM
Only if the md5sum number match with this: http://releases.ubuntu.com/10.10/MD5SUMS go to the next steps.

--- 4) burn the iso image onto a cd, to do it install and use http://infrarecorder.org/?page_id=5 burn the cd at lower speed you can do and activate the data verify

--- 5) insert the self made install cd into your pc cdrom drive and reboot your pc. YOU MUST NOT SEE Windows starting and you can try Ubuntu from cdrom and then install it

--- 6) If you have trouble with installation (the system freeze or you can't complete it) be sure to read the above suggestions, then:

Please boot entirely (you must not see windows starting) from Ubuntu live install cd and when the system start to boot from cd you will see two bottom screen icons ( keyboard and man inside circle ) please press space (choose your desired language) then a screen textual center menu will appear to you with this items in it:

Try Ubuntu without installing
Install Ubuntu
Check disc for defects
Test memory
Boot from first hard disk

Please select "Test Memory" to deeply test your ram healty, if your pc freeze at installation or installation doesn't start.

Please select "Check disc for defects" and press enter to test if your cd-driver can read in a good way the live install cd... or if the install cd have some defective files in it.
Then please also perform a Test memory to be sure your pc RAM memory have not any issue

Using this mode by pressing F6 you can select and add special kernel parameters that may help if the installation doesn't start

------

If you get a blank screen at boot after install or booting from the Ubuntu install cd please read:

http://www.ubuntugeek.com/how-to-fix-ubuntu-10-04-lts-lucid-blank-screen-at-startup.html

If you have trouble with intel8xxx graphic cards:

please try this: https://wiki.ubuntu.com/X/Bugs/Lucidi8xxFreezes

If you cannot boot you can also try some kernel boot options: https://help.ubuntu.com/community/BootOptions to solve.

--- 7) Ubuntu Manual, it's very informative: http://ubuntu-manual.org/
Click on the "download Button" to download the latest PDF version.

The online help https://help.ubuntu.com/10.04/index.html

--- 8) Relax and fun
http://planet.ubuntu.com/ and Full Circle Magazine http://fullcirclemagazine.org/

Thank you Marco for the speedy reply. I used the md5 instructions you provided and discovered that the signature of my downloaded version did not match the signature on the releases page.

My download: cac42832b05c5d67925b5618c7541478
Releases page: 59d15a16ce90c8ee97fa7c211b7673a8

This begs the question of how it is possible the file I downloaded directly from ubuntu.com does not match the signature that is also posted on ubuntu.com. I'm re-downloading to see if I can reproduce the issue or otherwise explain it.

Re-downloaded the ISO and this time the checksum matched. I can not think of anything that should have caused the first download to be bad, but in any event this does to address my issue. Thanks for the help!

We publish checksums exactly because it's possible for network-layer problems to occasionally corrupt data in transit. When you're dealing with 700MB of data in one go, the probability doesn't have to be all that high.

I just had this happen twice.

I was having the same problem with a old Dell Optiplex desktop even after checking md5sums. The problems was that I was using a rewritable CD (only those were handy). Solution was to use a standard CD-R and it worked like a charm.