When moving Mesh class / OBJ to fast it disapears

This is a giff this is what happens
![alt text][1]

litle bit more info, the game is a 3d side croller with mouse input function. So thats wahy mouse curser. Even when you hold the block stil in the air it wil automaticly go down, when i got it In the click (Not yet releast }. Sorry i have dislection SO bad eng XD whahaha
Do you guys know a way 2 fix this ??