Alright, so progress on my end. It looks like some of my player files were corrupted or something. I've had to delete two out of the four people who've tried logging in since I got it running again. I'm wondering if one of the item ID collisions might be the cause of this, although I believe my inventory had been unchanged since the last time I had logged in (mine was one of the bad user files.) It just crashed again, but just from running out of memory (is 3GB usage reasonable for 4 people being on a server at once?) Thanks for the advice so far.