Two explorer windows are open when I open an hard drive or usb key form Unity launcher

Binary package hint: unity

When I want to open a disk drive or USB key from the launcher unity, two windows are open.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: unity 3.8.2-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-7.39-generic-pae 2.6.38
Uname: Linux 2.6.38-7-generic-pae i686
NonfreeKernelModules: nvidia
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,resize,zoom,mousepoll,regex,grid,gnomecompat,move,vpswitch,place,wall,imgpng,mag,animation,wobbly,session,expo,unitymtgrabhandles,workarounds,ezoom,staticswitcher,fade,scale,unityshell]
Date: Sat Apr 2 14:07:41 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Beta i386 (20110330)
ProcEnviron:
 LANGUAGE=fr:en
 LANG=fr_CA.UTF-8
 LC_MESSAGES=fr_FR.UTF-8
 SHELL=/bin/zsh
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)