Usually when you start the surface with the cover closed on it. Another instance is when the main graphics driver crashes, and it uses the basic one instead
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\ImmersiveShell\Grid]
"Layout_MaximumAvailableHeightCells"=dword:00000005
"Layout_AvailableHeightCells"=dword:00000005
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Scaling]
"MonitorSize"="12.7"
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\ImmersiveShell\Grid]
"Layout_MaximumAvailableHeightCells"=dword:00000003
"Layout_AvailableHeightCells"=dword:00000003
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Scaling]
"MonitorSize"=-
The monitor size of 12.1 & 125dpi work great.