Running Ubuntu 12.10 my computer runs well and all seems OK. However sometimes when I shut down the screen hangs on the ubuntu sign with the dots underneath. If I go into a terminal by some means I see that it says it can't carry on because the core temperature is too high. Trouble is that leaving the computer on doesn't cool it down to make it continue with the shutdown process and all I can do is pull the plug. The computer doesn't feel hot. If I immediately switch back on all is well and during the boot process the BIOS shows the core temperature is 53C. Once the system is running I shutdown again and all is well.
Please, can anyone tell me what's happening?