mine has actually turned itself off a couple of times. I may have actually clicked something unknowingly but I've never really had a reason to hide my items. I got pestered with a LOT of Q's about my avi and I really don't care if someone copies me, I'll just change. Not like I ever have the same avi for too long anyway.
I know somepeople used to hide it to avoid scams and people triyng to hack their accounts... but there a lot more that hide to because they think people is going to steal their avis...It's very annoying, especially when I see that avis are in the feature avatar spotlight... I mean isn't the spotlight whole point to show off your avi and your items??