Trouble with the extruder

Hello,

I have a 3d robo printer and now when i am printing the extruder motor suddenly stops working and the temperture drops.
when i reconnect my usb, without shutting the printer off i can heat it up again.
once i start printing it takes some minutes and the same thing happens all over again.

Can anybody please help me ?

Preheating it by hand seems to work properly without suddenly dropping in temperture and having to re-connect the printer.

Thank you
Rogier

 

Does it throw up an error message? Open terminal: http://www.matterhackers.com/articles/mattercontrol-guide-to-the-terminal