I have a Sony Vaio VPCED33FM laptop. The O/S is W7 Home Premium. When W7 starts a loud high pitched screech sound from my speakers. If I plug in the headphones or external speaker to the headphone jack, the sound stops and I can hear or listen as usual. I tried a solution that required changes to the microphone properties other things I have tried but failed are: install of the latest driver, installed a new media board (not cable ribbon), USB board, and speakers. The power adapter was tested and works fine. The fan is clean. I haven't found anyone who has had the exact same problem. Some reported the high pitched sound when using certain applications, or had interference issues. I am hoping that someone can help me resolve this problem.