So here is how it goes.
- Open your Radiant 1.4
 -  Go to edit -> preferences -> Layout

 -  Now click at Use win32 file load dialogue so that it is deselected.

 -  If you save a map it's REALLY IMPORTANT that you write <yourmapname>.map. Really don't forget to wride .map

 
I hope it will help you and good luck with your maps.



