Hi Folks - well it looks like Rob was on the right track re panel states. I performed a number of test cases flying to TNCM as well as 4 other destinations using both the default and 777 Long panel states. In most cases, the brake overheating issue occurred only at TNCM and only when I loaded the 777 Long panel state. There were no issues when I loaded the default panel state and flew to TNCM. I fed the test results to PMDG and this was their response:
"John
I suspect this is one of the issues we discovered with the saved panel state files. There was a problem with the release version of the 777 that caused a lot of strange behaviour with saved panel states but it has been corrected for the upcoming SP1 update. Hopefully that will be released shortly. Let me know if you see this issue again after the SP1 update."