Hey everyone! So, I've trolled the importer forum all day and tried to find something specific to the problem that I'm having, but I cannot for the life of me figure this out. I'm going to try to be as detailed as possible. I really appreciate the help in advance

Okay, about 6 months ago, I inherited a moderately high traffic website. Most of the problems with the site comes from people abusing the forums. We're currently running 6.5.2, and the head hancho decided it was appropriate to upgrade to 7.3.1. I agreed.
The install went moderately smoothly. I was pleased with how nicely this forum just drops in and works from scratch. However, my boss would like to keep as much of the old forums as possible. We have something like 13k users and almost 2 million posts. I can only imagine how long that is going to take to import :-D
So, I tried running the importer. It looks as though it imports the groups correctly. However, once it hits the first user, that's it. No errors, no more than just that first user. I looked in the table, and it looks like the user information matches throughout the various tables.
I guess what I'm asking is, where do I go from here, since I can't even get my second user to import? And it doesn't help that the second user has an ellipsis in his username and html code in part of his information. Wouldn't surprise me if something in there is messing it up.
Again, I appreciate your help and your advice.