Opened DraftSight for the first time in a while today, and for some reason I can't see any lines on my model sheet - it shows the grid, but nothing else.  I have tried uninstalling (was the latest version anyway) and then reinstalling from a newly downloaded installer, but it hasn't made any difference... nor has changing the model background or making layers hidden and then unhidden.   Never had any problems like this before - any suggestions, anyone?