Duplicate icons sometimes appear and hovering over them causes a crash

Binary package hint: unity

I really thought I reported this before, but I can't find the bug. So forgive me if this is a dup.

Basically, occasionally duplicate launcher icons will appear briefly. This may be after switching to an app (like clicking on thunderbird) or when opening a new app. When this happens, a new launcher icon will appear right below the original one for one or two seconds, then disappear.

Moving the mouse over the icon will crash unity. If you avoid the duplicate icon, it will go away safely.

Next time it happens, I'll try to provide a stacktrace or more useful information.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: unity 3.6.8-0ubuntu3
ProcVersionSignature: Ubuntu 2.6.38-7.38-generic 2.6.38
Uname: Linux 2.6.38-7-generic x86_64
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,decor,mousepoll,vpswitch,regex,animation,snap,expo,move,compiztoolbox,place,grid,imgpng,gnomecompat,wall,ezoom,workarounds,staticswitcher,resize,fade,unitymtgrabhandles,scale,session,unityshell]
Date: Fri Mar 25 08:40:24 2011
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_GB.utf8
 LC_MESSAGES=en_US.utf8
 SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: Upgraded to natty on 2010-09-28 (178 days ago)