I opened up my draftsight and found that it is not functioning correctly.

When I draw a line and right click to finish it stays connected. I can only finish by pressing esc. I cannot do any of the modify functions. i can pick the lines I want to work on and highlight them but I then cannot carry out any of the functions that I require. like copy, move, etc etc have reinstalled the software. 

Have I inadvertently changed setting on my computer?

Any ideas anyone?