I know this was posted a while ago, but I have a similar problem.
Try with just a few select MP3s in the list… if my guess it right, it won’t crash when you sort them.
I’ve found that just DISPLAYING certain MP3s with ID3v2 tags in my list causes Zortam to crash (wish I knew of this bug before I registered, or I wouldn’t have). I don’t know what it is about those certain MP3s that does it, but it seems that if there’s a lot of information in the ID3v2 comment box, that’s when I get the problem. I think Zortam might have a limit on the number of characters in the field, where as the actual field itself does not, and so it crashes when its over Zortam’s limit. It would be nice to see this fixed, but it doesn’t seem like this website has been updated in a bout a year, so I doubt the chance of a new version coming out.