Crash when opting not to proceed with "new" Seq.

That's a known issue, however, it's not a show stopper, so the recommended advice is to either go ahead and setup a new file (you can then open the file you wanted, no need to save the new file) or you can let the program close out, open it again, and choose to open the file you were intending to open.   

There are also instances where File, Exit can cause the program to crash.  For that one, since the intent was to close the program, you can use the red "X" or simply let it error out.  That issue falls in the same boat as the above--  noted, and will be fixed at some point in the future.