Alt+Tab not always working

[Joaquin]

Binary package hint: unity-2d

Sometimes I can switch from a window to other, but sometimes, it shows the window preview on ALT+TAB switcher but not always switching...

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: unity 3.6.8-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-7.38-generic-pae 2.6.38
Uname: Linux 2.6.38-7-generic-pae i686
NonfreeKernelModules: nvidia
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,decor,grid,imgpng,snap,mousepoll,place,blur,regex,compiztoolbox,vpswitch,move,gnomecompat,wall,resize,kde,session,animation,workarounds,expo,ezoom,staticswitcher,fade,scale,unityshell]
Date: Thu Mar 24 15:06:15 2011
InstallationMedia: elementary
ProcEnviron:
 LANGUAGE=es_ES:en
 LANG=es_ES.UTF-8
 SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: Upgraded to natty on 2011-03-01 (22 days ago)