Hi Bob! I'm using a 74 minute disk. I have a MacBook ( so I won't be using the Sony software) and I want to do field recordings with the MZ-NF810 recorder. But it doesn't seem to record. The input display bar indicates sound is being recorded but I don't hear anything in the headphones. However, it does track mark, etc. But if I shut the machine off and start it back up then it reads as a blank disc. I've looked at the mic sensitivity and set it at high. I believe the recording mode was SP. The display also reads GP1, which I assume is group 1. I'd love to get rid of that also. Any thoughts? I'd appreciate any help you could provide. I have acquired the recorder second hand and I suspect it needs to be set to the original factory settings. I also do not have the remote with the headphones.