Comment 16 for bug 913273

I had the same problem with Lubuntu 14.04 when I started my computer (a laptop) with a second display.

A workaround is to turn off the second display automatically when the computer starts (in an autostart file in /home/user/.config/lxsession/Lubuntu) - I used xrandr --output VGA1 --off since I was using a vga monitor for my second display.

I then ran a desktop file then calls a bash file (perhaps overkill) that sets xrandr the way I want it.

I think that the key is that you have to get down to one display (your primary display) and then start up the second display. When I do it this way it uses the desktop image file correctly, and my pcmanfm cpu% never goes high.

Phil