where to report an desktop cd installer issue?

ubuntu desktop cd install hangs. amd64. ubuntu 11.10.
re-downloaded the cd image. verified checksum. verified burned cd. install always fails at about 80%. does not show details.

(downloaded alternate installer - same procedure - installation works! - so the desktop installer does something that fails. was reproducible. others had that - see google.. 'error 5 ubuntu installation'

same problem that one mentions:

http://www.adminscode.com/ubuntu-ubuntu-11-10-installation-error-5-inputoutput.html

starting citation:

[ubuntu] ubuntu 11.10 installation error 5 input/output
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I’m trying to install Ubuntu 11.10. i am getting the following error:
This particular error is often due to a faulty CD/DVD disk or drive, or a faulty hard disk. It may help to clean the CD/DVD, to burn the CD/DVD at a lower speed, to clean the CD/DVD drive lens (cleaning kits are often available from electronics suppliers), to check whether the hard disk is old and in need of replacement, or to move the system to a cooler environment.

i have only one RAM so i can’t remove it also my RAM and hard disks are working properly.:(:(

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