I'm not sure this is completely repeatable, I'll need to try it again, but here is what I think I noticed..
All of my directories and txt filenames are in the following convention:
Artist Name - Track Title
I have a directory & .txt file that have an ampersand in the band name. When loading this file [by pressing "s" after the intro page displays]the program would segfault and dump memory. Then I replaced the "&" with "and" in the file and directory names and ultrastarng started normally.
The thing that gives me hesitation in this is that I have another file where the track title contains an "&", but it did not cause the segfault problem...