Installer crashes when partition mounted

Forme it seems asif installer crashesbecause ubiquitywas startedwith debug mode - with kd-eui missing.

Tryed something like that:
kdesu env UBIQUITY_DEBUG=1 ubiquity kde-ui 2 >/tmp/ubiquity.log

Now it doesn't crash on starting partitioning dialogue, but logfile is empty....
Can be closed?!

There's loads of this stuff, which is the cause of the problem (nothing to do with partitions being mounted, as far as I can tell):

Oct 3 13:29:12 ubuntu ubiquity: Xlib: connection to ":0.0" refused by server^M

Any idea why?

Oh, sudo probably isn't preserving DISPLAY or some KDE-specific environment variables. That would do it. kdesu is more likely to work.