To force quit an application, you can go to the Apple menu (top left) and choose force quit and then the application. You can also do the same on the dock. Click and hold till a sub-menu comes up.
As far as crashing when saving, do a get info command on the folder you are saving to, (apple key and "I" together ) and check the privilege for it. It needs to be set for read AND write. It can cause problems if the folder isn't allowed to write to it.
You should also use disk utility (finder-apps-utilities-disk utility) and repair permissions for the disk.
Also, it is helpful when you post, to list which Mac and OS you are using.