opendx processes do not stop when user quits the program

Binary package hint: dx

I start OpenDX using the command "dx" and do some visualisation work with it, including editing a visualisation scheme (build from various blocks) and executing it.

At the end I normally quit the program.

After this quitting there are still opendx processes in the system, namely dx and dxexec:
  PID TTY TIME CMD
 2451 pts/1 00:00:01 bash
21296 pts/1 00:00:00 dx
21331 pts/1 00:05:56 dxexec
21452 pts/1 00:00:00 ps

The dxecec process consumes 100% CPU (all power of one processor core).

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: dx 1:4.4.4-3build3
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Tue May 24 11:22:10 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
ProcEnviron:
 LANGUAGE=en
 PATH=(custom, user)
 LANG=en_GB.utf8
 LC_MESSAGES=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: dx
UpgradeStatus: No upgrade log present (probably fresh install)