So here is the problem for all of you who couldn't get through all the junk on this thread...(too many people trying to talk about spelling and junk...)
OP (original poster) puts computer into stand-by or hibernate but when he moves the mouse or hits a button on the keyboard it won't 'wake-up'. OP has set the bios settings to 'wake on mouse/keyboard'. It use to work and now it doesn't. OP has to use the power button on the tower to wake the computer.
Here is my 2 cents. First I wouldn't expect the computer to wake from hibernation using the keyboard or mouse because they would be turned off. The computer goes into an ultra-low powerstate and is 'almost' turned off. However, it should be able to wake from stand-by using either one. What I would do is disable hibernation and see if that helps any. Sometimes having it enabled and not using it cause issues. Also, do you have it set to ask for a password when it wakes? If so try turning that off. We can see if that helps. If you have another keyboard, it wouldn't hurt to try it. It might not make a difference but it won't hurt. Also, turn the System Stand-by after: to never. See if that helps. We can start with these settings and work our way out to see if we can discover the issue. Also if you have only recently enabled the wake up on keyboard/mouse in your BIOS, set it back to whatever it was and see if that affects it at all.