Interesting point about combining chapters. On a self made DVD, each chapter point goes back to the menu which causes a momentary picture freeze. Is that your symptom ? PM me if you want to swap info.
Another point - although it has long recording capabability, the 5100 will only record for a maximum of 6 hours at a single title, whichever way you set it up, either "one touch" or timed, even to the hard drive. Do any other machines offer more ?
No discernable disc noise tho.