Upgrade from Xubuntu 14.10 to 15.05 (Update history : 13.10 -> 14.04 -> 14.10 -> 15.04). The upgrading worked well. After rebooting the machine (Dell Inspiron 6000 - 10 years old) went automatically into sleep. Leaving sleep is easy but seems to be timed! (When you don't enter you password in a few seconds, it starts sleeping again). Once logged in, you can't power down the machine, it simply goes into sleep! The only way to go into powerdown is via "sudo shutdown now" command. Is there a way to fix this behaviour such that I become a normal powering up/down-behaviour? I already tries some of the xfce4-power management settings, but nothing seems to help (computer gives the logoin-screen again).
Some other oberservations. Even shutting down via the top-right button on the welcome-screen doens't succeed.