After I log in, the screen flashes white then goes black. This first happened after I changed the display settings (monitor default change). I've since tried to change this back by following this post
The solution:
Adding these few lines (shown in bold below) to the /home/user/.kde/share/config/krandrrc solved it thanks to the second post by ranacc here http://ubuntuforums.org/archive/index.ph...8236.html.

[Display]
ApplyOnStartup=true
SyncTrayApp=true

[Screen_0]
OutputsUnified=false
UnifiedRect=0,0,0,0
UnifiedRotation=1

[Screen_0_Output_default]
Active=true
Rect=0,0,1280,1024
RefreshRate=85
Rotation=1