Comment # 9 on bug 40024 from Christopher M. Penalver

Roberto Grassi, Xubuntu 11.04 reached EOL on October 28, 2012. For more on
this, please see https://wiki.ubuntu.com/Releases.

If this is reproducible with a supported release, it will help immensely if you
filed a new report with Ubuntu by ensuring you have the package xdiagnose
installed, and that you click the Yes button for attaching additional debugging
information running the following from a terminal:
ubuntu-bug xorg

Also, please feel free to subscribe me to it.

For more on why this is helpful, please see
https://wiki.ubuntu.com/ReportingBugs.