I'm new to QGIS and have been seeing what it can do for me – seems good. I imported shape file data from a UK Ordnance Survey data file and saved the file in a new folder. It was very good, doing all I wanted. I exported and got exactly what I wanted ( a tiff image).
I closed the file in order to try a new experiment. When I went to re-open it I got a dialogue box saying 'Handle Bad Layers. I don't understand what is at issue and what to do.