cubase sx and vistax64

can anyone help im using vista x64 and cubase sx and my midi in keeps losing its connection,so i cant record,ahhhhh,,

any suggestions,

steve

could you post what midi device are you using? Both cable and midi keyboard.

im using a yamaha clavinova cvp401 with the usb cable straight into my computer,sound card cake walk sps 66, the midi input is active when i turn it on but then it looses it after about 15 mins,