No Response to iMac keyboard or trackpad (wired or usb) Problem: mid2011 iMac Mavericks was operating perfectly.  Logged off, powered down.  Next morning, powered up; system boots normally to login screen.  No response to keyboard or trackpad...trackpad light blinks trying to link but will not.  

Attempted: Tried usb keyboard no change.  Tried all usb ports no change.
Plugged keyboard into macbook...works normally; wireless keyboard and trackpad too.
Removed batteries from kybd and trackpad; powered up iMac with nothing plugged into ANY port. System boots to login screen but does NOT prompt "No Keyboard or Mouse Found" as it should.
HELP!
Try resenting your SMC (system management controller)

Do this: Remove the iMac from the AC main power (shut it down first) by removing the plug from the outlet. Let it set that way for 15 minutes. Plug it back in and restart.