Installation of 12.04 alpha 1 amd64 fails on my machine

[Mossroy]

Install has been made from an USB stick.
I checked the option to download updates during install.
I previously managed to install the 32-bit version on this same machine, but maybe something else was different

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.9.5
ProcVersionSignature: Ubuntu 3.2.0-2.5-generic 3.2.0-rc3
Uname: Linux 3.2.0-2-generic x86_64
ApportVersion: 1.90-0ubuntu1
Architecture: amd64
CasperVersion: 1.292
Date: Fri Jan 6 14:10:26 2012
LiveMediaBuild: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20111129.1)
ProcEnviron:
 LANGUAGE=
 PATH=(custom, no user)
 LANG=fr_FR.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Mossroy (mossroy)]

I managed to do the install by unchecking the options to download updates and mp3 codec, before installing.
Then, after the install, downloading and installing all updates worked fine.