This is not a severe problem, but rather something wierd that happens every once in a while. I noticed it started last summer.
My brother was using my computer and when he shut it down, everything turned off except, it didn't totally turn off. I'll try to explain this the best I can. Usually, on a regular shutdown, everything turns off, and just as everything goes quiet, I hear my fan wind down, that's usually the signal that everything is powered down.
Now, sometimes, I'll set it to shut down, it'll start it's shut down procedure, and at the moment when everything should power down, some stuff stays running. To be more specific, the power supply is still running it's fans, still providing power, all the LEDs are still on, but everything else in the computer has shutdown. To complete the shutdown, I have to hold the power button.
Has anyone ever seen this or had this happen to them? If you got a suggestion, throw it out there.