gnome-system-monitor crashes when killing root process

Binary package hint: gnome-system-monitor

i'm trying to kill a process owned by root using gnome-system-monitor.
it used to invoke GKSU, but not it just closes it self
$ gnome-system-monitor

** (gnome-system-monitor:28409): WARNING **: SELinux was found but is not enabled.

The program 'gnome-system-monitor' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadMatch (invalid parameter attributes)'.
  (Details: serial 121038 error_code 8 request_code 1 minor_code 0)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

ProblemType: Bug
Architecture: amd64
DistroRelease: Ubuntu 9.04
NonfreeKernelModules: nvidia
Package: gnome-system-monitor 2.26.0.1-0ubuntu1
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-system-monitor
Uname: Linux 2.6.28-12-generic x86_64