Comment 12 for bug 145836

I have exactly a same problem. I believe the frozen process is from /lib/partman/init.d35/dump. The following line is frozen:

rm /var/log/partition_dump

The problem is for some reasons directory /var/log is locked (I can't even list files in the directory) when the installer is running.

My workaround is just comment the line before run the installer. It works.