Cannot load the Qt platform plugin "xcb"

Hi,

yesterday I installed Qt 5.10 on my Virtual Box VM with Ubuntu 14.04. I had some disk space problems and so uninstalled many old unneeded Linux Kernel versions. Now Qt 5.10 is completely installed. But my QtCreator 3.6.0 doesn't start any more:

This application failed to start because it could not find or load the Qt platform plugin "xcb".
Available platform plugins are: linuxfb, minimal, offscreen, xcb.
Reinstalling the application may fix this problem.

I read several issues here (and otherwhere), but not any seems to solve my problem. I tried to start qtcreator.sh, but gives the same error. Here is the output of ldd ...qtcreator-3.6.0/lib/Qt/plugins/platforms/libqxcb.so:

    linux-vdso.so.1 =>  (0x00007fff54b50000)
    libQt5XcbQpa.so.5 => /opt/hacon/build/qt/5.10.0/lib/libQt5XcbQpa.so.5 (0x00007fdd3e5f5000)
    libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fdd3e134000)
    libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007fdd3df32000)
    libXi.so.6 => /usr/lib/x86_64-linux-gnu/libXi.so.6 (0x00007fdd3dd22000)
    libSM.so.6 => /usr/lib/x86_64-linux-gnu/libSM.so.6 (0x00007fdd3db1a000)
    libICE.so.6 => /usr/lib/x86_64-linux-gnu/libICE.so.6 (0x00007fdd3d8fe000)
    libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007fdd3d6df000)
    libfontconfig.so.1 => /usr/lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007fdd3d4a3000)
    libfreetype.so.6 => /usr/lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007fdd3d200000)
    libQt5DBus.so.5 => /opt/hacon/qt/qtcreator-3.6.0/lib/Qt/plugins/platforms/../../lib/libQt5DBus.so.5 (0x00007fdd3cf84000)
    libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007fdd3cd82000)
    librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fdd3cb7a000)
    libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007fdd3c872000)
    libXrender.so.1 => /usr/lib/x86_64-linux-gnu/libXrender.so.1 (0x00007fdd3c668000)
    libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007fdd3c456000)
    libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007fdd3c121000)
    libQt5Gui.so.5 => /opt/hacon/build/qt/5.10.0/lib/libQt5Gui.so.5 (0x00007fdd3bb63000)
    libQt5Core.so.5 => /opt/hacon/build/qt/5.10.0/lib/libQt5Core.so.5 (0x00007fdd3b5e3000)
    libGL.so.1 => /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1 (0x00007fdd3b37d000)
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fdd3b15f000)
    libstdc+.so.6 => /usr/lib/x86_64-linux-gnu/libstdc+.so.6 (0x00007fdd3ae5b000)
    libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fdd3ab55000)
    libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fdd3a93f000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fdd3a576000)
    /lib64/ld-linux-x86-64.so.2 (0x00007fdd3e53a000)
    libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007fdd3a371000)
    libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007fdd3a16d000)
    libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007fdd39f67000)
    libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007fdd39d3d000)
    libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fdd39b24000)
    libpng12.so.0 => /lib/x86_64-linux-gnu/libpng12.so.0 (0x00007fdd398fe000)
    libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007fdd396c0000)
    libicui18n.so.58 => /opt/hacon/build/icu4c/58.2/lib/libicui18n.so.58 (0x00007fdd39249000)
    libicuuc.so.58 => /opt/hacon/build/icu4c/58.2/lib/libicuuc.so.58 (0x00007fdd38e9f000)
    libglapi.so.0 => /usr/lib/x86_64-linux-gnu/libglapi.so.0 (0x00007fdd38c78000)
    libXdamage.so.1 => /usr/lib/x86_64-linux-gnu/libXdamage.so.1 (0x00007fdd38a75000)
    libXfixes.so.3 => /usr/lib/x86_64-linux-gnu/libXfixes.so.3 (0x00007fdd3886f000)
    libxcb-glx.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0 (0x00007fdd38658000)
    libxcb-dri2.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri2.so.0 (0x00007fdd38453000)
    libxcb-dri3.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri3.so.0 (0x00007fdd38250000)
    libxcb-present.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-present.so.0 (0x00007fdd3804d000)
    libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007fdd37e47000)
    libxshmfence.so.1 => /usr/lib/x86_64-linux-gnu/libxshmfence.so.1 (0x00007fdd37c45000)
    libXxf86vm.so.1 => /usr/lib/x86_64-linux-gnu/libXxf86vm.so.1 (0x00007fdd37a3f000)
    libdrm.so.2 => /usr/lib/x86_64-linux-gnu/libdrm.so.2 (0x00007fdd37831000)
    libicudata.so.58 => /opt/hacon/build/icu4c/58.2/lib/libicudata.so.58 (0x00007fdd35d31000)

I don't see any problem with so files here. Who can help???

Kind Regards

TK