From time to time I get crashes with RealCADD – and once it happens, it often seems to get progressively worse.
I've known for some time that arcs in particular can, for some reason, get created without a centre, that is xc = NAN and yc = NAN (perhaps Eric will know why ...). I think it is possibly when using the fillet tool but failing to get a fillet. And if you have one of these in your drawing it will likely cause a crash, to the point where trying to select anything, or draw a marquee with the select tools, will cause a crash.
The solution: easy!!
Go to Edit >> Special Select. Click the "None" button and then check the "Arcs" box (which will make it go to the "Some" button). Check the "Length object = 0 or empty string" box and hit OK. This will select all "empty" arc objects. If you have arcs with a NAN centre, or a zero length, they will show in the Edit pallet. Simply hit the delete key and they are gone!
It's so obvious when you think about it – but I've been using RC for years without realizing what that box was for ...
You can repeat the process with other objects that may be "empty" (lines, rectangles etc). On a drawing that was crashing badly recently, I removed three empty arcs and I also found that I had several empty lines as well, and I removed them. It has been rock solid since.
I will add a paragraph about this to the Manual.
Cheers -- George