* Try to de-humidify the room.
* Make sure curtins/blinds do not cut off air circulation to windows.
* Try a fan blowing air at the window.
* Humidity in the air is condensing on the window glass, then flowing down where it collects at the bottom of the pane.
* If all else fails, then it;s time for thermal windows...
* Good luck... Adios... Jasper