This is the way windows 8 works. Hibernation and Hybrid Sleep require a brief press of the power button to wake the computer. If a key press doesn't work it means the computer is in Hybrid Sleep so you have to  press the power button.
Used MS Upgrade adviser to Upgrade to Windows 8. All went well. Only issue: when the computer goes to sleep, I can't wake it up with the keyboard or mouse. I  have to hit the power button. AFAIK: My BIOS is up to date. All My drivers are up to date. I have not modified the machine in any way. Recommendations?
XPS 435 MT Windows 8 Wake up