I'm looking for some help with an Acer XC-705 Aspire desktop PC. The symptoms are that if the PC is left doing nothing (just on), when you return to it, it has restarted itself. Checking event viewer, under the title critical, it says the PC turned off without being shutdown correctly. If the PC is being used, it never happens, only when idle. It can do it as it boots itself up after one of these events as well. The other night I left it on and it did it five times. Some days it doesn't do it. I have replaced the power supply, updated the BIOS, blown all the dust out of the fans, replaced the hard drive, reinstalled the operating system and carried out updates. I also have the older XC-600 which does exactly the same thing. Any help would be appreciated. Regards, Nigel.