Kubuntu Desktop AMD64 - ubiquity kde_ui crash with File "/usr/lib/python2.7/dist-packages/debconf.py", line 70, in command self.write.flush() IOError: [Errno 32] Broken pipe

Binary package hint: ubiquity

ISO Kubuntu Desktop AMD64 / 2011.01.31

Ubiquity crashes after clicking on 'forward' at step 'Who are you'. The following error is caught is syslog
Works fine on i386

Jan 31 12:00:37 ubuntu ubiquity[5400]: Step_before = Form
Jan 31 12:00:39 ubuntu install.py: Exception during installation:
Jan 31 12:00:39 ubuntu install.py: Traceback (most recent call last):
Jan 31 12:00:39 ubuntu install.py: File "/usr/share/ubiquity/install.py", line 610, in <module>
Jan 31 12:00:39 ubuntu install.py: install.run()
Jan 31 12:00:39 ubuntu install.py: File "/usr/share/ubiquity/install.py", line 124, in run
Jan 31 12:00:39 ubuntu install.py: self.copy_all()
Jan 31 12:00:39 ubuntu install.py: File "/usr/share/ubiquity/install.py", line 391, in copy_all
Jan 31 12:00:39 ubuntu install.py: self.db.progress('SET', 10 + copy_progress)
Jan 31 12:00:39 ubuntu install.py: File "/usr/lib/python2.7/dist-packages/debconf.py", line 65, in <lambda>
Jan 31 12:00:39 ubuntu install.py: lambda *args, **kw: self.command(command, *args, **kw))
Jan 31 12:00:39 ubuntu install.py: File "/usr/lib/python2.7/dist-packages/debconf.py", line 70, in command
Jan 31 12:00:39 ubuntu install.py: self.write.flush()
Jan 31 12:00:39 ubuntu install.py: IOError: [Errno 32] Broken pipe

TEST CASE:
1. Boot from LiveCD Kubuntu-Desktop-AMD64
2. Try KUbuntu
3. Click on 'Install KUbuntu'
4. Follow the installation steps

Result:
- Ubiquity closes after step 'Who are you'

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: ubiquity (not installed)
ProcVersionSignature: Ubuntu 2.6.38-1.28-generic 2.6.38-rc2
Uname: Linux 2.6.38-1-generic i686
Architecture: i386
Date: Mon Jan 31 12:52:20 2011
EcryptfsInUse: Yes
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.utf8
 LC_MESSAGES=en_US.utf8
 SHELL=/bin/bash
SourcePackage: ubiquity