Acer Aspire 4520-5582 Notebook "stereo center speakers work time" Questions

...stereo babyphone jack to connect to external speakers. This jack has a built-in switch that cuts off internal speaker if an external is plug in. If you are using eternal or headset from time to time, ...

...center (the PC is then put in some kind of "standby" mode) and try again the next day. Until now this has always worked. When the problem occurs, everything SHOULD be working but it doens't. The ...