crash before install complete (second attempt)

[Andrej]

firs crash report was at https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/970289

i hawe disk with 4 primary partitions, i trying install Ubuntu on third.
when installing, i select to download updates and to install restricted extras.
i select location Riga, and Latvian keyboard layout.
i select to use /dev/sda3 as ext4 and as "/".
i select to install boot loader on /dev/sda3.
skip creation of svap partition.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.10.4
ProcVersionSignature: Ubuntu 3.2.0-20.33-generic 3.2.12
Uname: Linux 3.2.0-20-generic x86_64
ApportVersion: 1.95-0ubuntu1
Architecture: amd64
CasperVersion: 1.312
Date: Sun Apr 1 18:49:53 2012
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120328)
ProcEnviron:
 LANGUAGE=en_US.UTF-8
 TERM=linux
 PATH=(custom, no user)
 LANG=en_US.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)