I see this problem in Hardy. Note that I successfully added 'cpugraph'
once, the problem may only have occurred after I removed it and
attempted to re-add it. I have not (yet) found a work around. The
following was logged into ~/.xsession-errors
The program 'xfce4-cpugraph-plugin' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadAlloc (insufficient resources for operation)'.
(Details: serial 187 error_code 11 request_code 53 minor_code 0)
(Note to programmers: normally, X errors are reported asynchronously;
that is, you will receive the error a while after causing it.
To debug your program, run it with the --sync command line
option to change this behavior. You can then get a meaningful
backtrace from your debugger if you break on the gdk_x_error() function.)
** Message: CPU Graph: screen changed: 0