If you are comfortable with editing the registry, you can do this: (Make a registry backup, before you start!)
Open the registry (Type Regedit), and go to this registry key:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\ImmersiveShell\Grid (CurrentVersion is one long string, but for some reason I cannot edit it as such)
In the right pane of Registry Editor search for the entry Layout_MaximumRowCount. If it does not exist, you will have to create it. To do this, right-click on a empty space in the right pane of Grid, click on New and DWORD (32-bit) Value, type
Layout_MaximumRowCount
and press Enter.
If it is already there, set its value to a number higher or...