Some points to check:
Does Windows see the camera when you connect it to your computer?
Do you switch the camera on before you start Media Composer? Sometimes MC doesn’t see a deck if it was only switched on after MC was started.
Are your project settings exactly the same as your camera recording settings? If not this might explain the “you may not capture or log audio and video together because they are being input at different rates” message. In particular did you record your audio in the camera at 48bit or 32bit. MC can be fussy if the audio was not recorded at 48bit.