I started out playing the Singleplayer example level Hereafter first. It worked fine, until I AV'ed out by going through the Blue Key door (where you press Up to travel through) too many times too quickly.

Things worked fine after that until I played the FunPak level, where I AV'ed out again (can't remember what did it, but it was something close to the beginning of the level).

Now that I think about it, this may be a new crash, since some levels work, but not others. I tested all of the following on Singleplayer:

Hereafter, Cerulean Comet, Player Timer, Multiple Exits (and the secret level), Jailbreak, Tetris, Limit X Scroll, Quick Diamonds, I'm Going to Hell Anyway (although it did AV out when I did JJnext), and Butterfly all seem to work normally enough.

FunPak (it works briefly, but after running around a little bit either freezes up or just crashes), Flag Run (this one crashed on me after I died from taking a Red flag to a Blue base), Domination (it AV'ed out altogether), Angelscript (I got into the level, but then it AV'ed out), and Survivor (it AV'ed out altogether) all have problems.

I tried setting Player 1 characteristics for Multiplayer (name, colors, rabbit, controller) to normal, non-custom settings, and I both played my own hosted LAN game on the Battle1plus map (which worked) and joined one of the Jazz2Online servers (which also worked), but my singleplayer still doesn't fully function.