Can you check the system info screen to tell us the exact temperature? How old is this HR10? Does the unit have good ventilation?
I opened my case and put an external fan pointing at the tivo so I could get it to stay up long enough to monitor the temp in settings. Otherwise mine would shut down during the sat signal aquisition.The error comes up right after starting up so you can't access any menus to see if the temp is actually high.