unable to mount .iso file

I get this:

Building failed.

Please look at /home/clayton/tmp/build.log to see what went wrong.

If you cannot find the problem, please send a support request at:

 https://launchpad.net/products/uck/+addticket

and also this in the terminal:

Preparing build environment...
Creating X authentication cookie...
Running build process...
Build (/usr/bin/uck-gui --wait-before-exit) started at 2014-07-10 11:43:31
[sudo] password for clayton:
>> Ubuntu Customization Kit 2.4.7 on Ubuntu 14.04, 3.13.0-30-generic i686
Starting CD remastering on Thu Jul 10 11:43:35 CDT 2014
Customization dir=/home/clayton/tmp/customization-scripts
Removing ISO remastering dir...
Mounting ISO image...
mount: block device /home/clayton/Desktop/ubuntu-14.04-desktop-i386.iso is write-protected, mounting read-only
Unpacking ISO image...
cp: error reading '/home/clayton/tmp/remaster-iso-mount/casper/filesystem.manifest': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/casper/filesystem.manifest': Input/output error
cp: error reading '/home/clayton/tmp/remaster-iso-mount/casper/filesystem.manifest-remove': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/casper/filesystem.manifest-remove': Input/output error
cp: error reading '/home/clayton/tmp/remaster-iso-mount/casper/filesystem.size': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/casper/filesystem.size': Input/output error
cp: error reading '/home/clayton/tmp/remaster-iso-mount/casper/filesystem.squashfs': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/casper/filesystem.squashfs': Input/output error
cp: error reading '/home/clayton/tmp/remaster-iso-mount/casper/initrd.lz': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/casper/initrd.lz': Input/output error
cp: error reading '/home/clayton/tmp/remaster-iso-mount/casper/vmlinuz': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/casper/vmlinuz': Input/output error
cp: error reading '/home/clayton/tmp/remaster-iso-mount/isolinux/access.pcx': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/isolinux/access.pcx': Input/output error
cp: error reading '/home/clayton/tmp/remaster-iso-mount/isolinux/blank.pcx': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/isolinux/blank.pcx': Input/output error
cp: error reading '/home/clayton/tmp/remaster-iso-mount/isolinux/splash.pcx': Input/output error
cp: failed to extend '/home/clayton/tmp/remaster-iso/isolinux/splash.pcx': Input/output error
Unmounting /home/clayton/tmp/remaster-iso-mount...
Failed to unpack ISO from /home/clayton/tmp/remaster-iso-mount to /home/clayton/tmp/remaster-iso