Hi urgent,
Looks like this could be an intermittent type of problem. Neemo most likely hit on the problem in Post #26 which is a very common problem with laptops. Since you mentioned your Sony is an All-in-one PC, it's kind of a hybrid between a desktop PC and a laptop. So, depending on how it's constructed, it may or may not have an Inverter, and that repair Neemo mentioned may not be applicable to your specific machine.
Having read over the thread and possible solutions, the one thing that's not clear is whether or not you are plugging in the AC Power Adapter directly to a 120VAC wall outlet or into a Surge Protector. If you are plugging in that Power Adapter to a Surge Protector such as this:
And your Surge Protector has failed on one or more outlets, you could get the appearance of a Sleep or Hibernation condition on your computer due to that failure. The easiest way to rule this out is to temporarily remove the Surge Protector from the wall outlet you have it plugged into, and plug your PC's power adapter
DIRECTLY into the wall outlet and retest. If it works normally and your PC no longer goes to sleep, then your Surge Protector has failed and must be replaced. And you should replace it if it has failed, and it's a crucial protection to keep your computer from getting hit by a lightning strike from an electrical storm, thunderstorm, hurricane, or tornado. The cost is minimal--$10-$45 and is well worth the cost.
Should the problem persist after trying the above, it's possible you either live in an older home with no
GFI (
Ground
Fault
Interruption protection), and you have a problem with that particular outlet. An easy way to test this it to try another outlet in your home, preferably in a different room where you currently operate your computer, such as a kitchen, garage, or bedroom which is on a different breaker in your breaker panel. If the problem persists with other wall outlets in your home, it's quite likely you have a house wiring fault. There are cheap testers ($10) you can buy at your local hardware, computer, or radio shack stores that you can plug into your wall outlets that will give you a led display that will tell you if you indeed have a home wiring fault. Or you can call an Electrician in and pay to have him test it; as you will need a licensed Electrician to fix this problem anyway. They can test your outlets and tell you in 5 min. whether or not you have this particular problem. If you do, the Surge Protector is not your problem, but rather a ground fault in your house wiring.
Since we don't know what part of the country you live in, or even if you are outside the US, but if you are in Europe or the Eastern seaboard of the U.S., many homes can be 50 to hundreds of years old. GFI technology is installed in most homes and mobile homes built in the U.S. in the last 40 years or so (70s); if your home is older than 40 years, it's quite likely you don't have GFI, and there are other things that can be done--
often up to and including very expensive whole home rewiring with an entirely new breaker panel!! If your home is newer than 40 years old and in the U.S., it's usually a fairly simple repair by an electrician, often the fault is just an broken receptacle, or breaker (fuse) and can be fixed in a couple of hours!
GFI faults can often occur without a homeowner's knowledge, and can cause this exact type of problem. I've seen it many times over the years. Home computer users are often astonished by this problem, as they forget the power that comes into their home is the energy source that powers the computer; if that's not clean power or somehow faulty, your computer can and will display many what appear to be weird problems.
A GFI problem could explain why your PC works at the Geek Squad repair bench but not at your home!! In the situations where I correctly identified a GFI fault, and it was subsequently repaired by an Electrician the homeowner retained, and then plugged the computer back into the wall outlet (and subsequently into the Surge Protector which was then plugged into same wall outlet), everything worked normally!!
If you pursue these steps and ensure you don't have a faulty Surge Protector or home wiring GFI fault, I suggest you return the computer to Best Buy for servicing.
Best of luck,
<<<BIGBEARJEDI>>>