Sometimes(about twice in 10 minutes or above) I couldn't stop my chracater though I released my keyboard! It gets me repeat jumping or walking.... And it's very annoying when I falled down to LAVA. I can stop those stupid loops easily by pressing ESC, but few minutes later, it's jumping again! I died several times with this glitch. (Forget about 1.4.6, Sometime I got this symptom at older version... Some versions was OK, others not.)