Hi Have a problem. My computer keeps making a 'pop' sound sometimes when I am working at it and sometimes when no one is near to it. The screen then goes black and the comuter has turned off. Turn back by the power button and then it is OK again for awhile. Doing this about 2 or 3 times a day now. Anyone else experienced this problem and how to resolve please. Have asked other people but can't find anyone else who has had the problem.