Comment 15 for bug 1295267

Yes, I'm experiencing the same thing.
After a lock screen, my windows all move back onto one monitor.

The main monitor has had the resolution dropped from 3840x2160 --> 2560x1440

Linux worky 3.19.0-18-generic #18-Ubuntu SMP Tue May 19 18:31:35 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
unity 7.3.2

Graphics: Card: NVIDIA GK104GLM [Quadro K3000M] bus-ID: 01:00.0
           Display Server: X.Org 1.17.1 drivers: nvidia (unloaded: fbdev,vesa,nouveau)
           Resolution: 1920x1080@59.9hz, 1920x1080@60.0hz, 2560x1440@60.0hz
           GLX Renderer: Quadro K3000M/PCIe/SSE2 GLX Version: 4.5.0 NVIDIA 346.59 Direct Rendering: Yes

$ xrandr
Screen 0: minimum 8 x 8, current 5560 x 1920, maximum 16384 x 16384
VGA-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected primary 1080x1920+2560+0 left (normal left inverted right x axis y axis) 531mm x 298mm
   1920x1080 59.9*+
   1680x1050 60.0
   1600x1200 60.0
   1440x900 59.9
   1280x1024 60.0
   1280x960 60.0
   1280x800 59.8
   1024x768 60.0
   800x600 60.3 56.2
   640x480 59.9
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 connected 1920x1080+3640+13 (normal left inverted right x axis y axis) 382mm x 215mm
   1920x1080 60.0*+
DP-5 disconnected (normal left inverted right x axis y axis)
DP-6 connected 2560x1440+0+0 (normal left inverted right x axis y axis) 607mm x 345mm
   3840x2160 60.0 +
   2560x1440 60.0*
   1920x1080 60.0 59.9
   1680x1050 60.0
   1600x900 60.0
   1440x900 59.9
   1280x1024 75.0 60.0
   1280x800 59.8
   1280x720 60.0
   1152x864 75.0
   1024x768 75.0 70.1 60.0
   800x600 75.0 72.2 60.3 56.2
   640x480 75.0 72.8 59.9