Oh no! I hope you didn't loose any work due to these bugs!
I have fixed the crash bug and changed the format of the filenames when saving an image sequence.
It now names the files as:
'{selected_filename}_map_XX.EXT' where XX is the map number and EXT is the file extension of the selected file (default is png).
My hope is that by adding '_map_XX' instead of just 'XX' there's less chance the sequence file names will conflict with other naming conventions you might be using. Hope that works for you, if not, let me know and we can come up with something better.