Ubiquity fails to proceed to step partman on amd64

[Jean-Baptiste Lallement]

Binary package hint: ubiquity

Desktop ISO Testing: Ubuntu Desktop AMD64 20110223
Testing Env: VBox

When clicking on 'Forward' on step Prepare, Ubiquity fails to proceed to step partman. The Forward button switch to a 'disabled' state, the cursor changes to hourglass, but nothing happens.

Works fine on i386

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: ubiquity 2.5.16 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 2.6.38-4.31-generic 2.6.38-rc5
Uname: Linux 2.6.38-4-generic x86_64
Architecture: amd64
Date: Fri Feb 25 13:23:53 2011
LiveMediaBuild: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110223)
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 LC_MESSAGES=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity