few minutes after starting of insallation , it stops and and report to me that there is a problem with a disc

[zoran popov]

installation is almost finished....but at the end it stops and show me that there is a problem with a disc.
It shows that I have to change the disc on my combuter because it is to old

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubiquity 2.18.8 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 3.13.0-32.57-generic 3.13.11.4
Uname: Linux 3.13.0-32-generic i686
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: i386
CasperVersion: 1.340
Date: Thu Oct 2 10:29:24 2014
InstallCmdLine: file=/cdrom/preseed/xubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Xubuntu 14.04.1 LTS "Trusty Tahr" - Release i386 (20140723)
ProcEnviron:
 PATH=(custom, no user)
 LANG=hr_HR.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Phillip Susi (psusi)]

Your installation medium is corrupt; please recreate it and try again.