From what i can see, it seems you've avoided hitting a Foreground to Background point, leaving you with no place to land on except possibly loops. If you are able to recreate this, try and film every bit. My guess is this happened after you went through a loop.
I could still hit enemies, power ups & spikes, but I couldn't hit any floors or walls whatsoever. I'm not sure about loops though, if I can get a ROM of this game & a NDS emulator going on my PC I can try & replicate this again, you are right in saying this happened around a loop, cuz it did. Can't do this on my DSi unless I get another one, would be my 4th DSi, I've already broken 2 R buttons ring attacking this game.
EDIT- Well actually what happened is I was standing inside a wall, and then I walked off the apparent floor I was standing on, then this started happening.