I have seen some similar posts, but nothing exactly like this.  The various command buttons (copy, fax, number keys, etc.) have stopped responding consistently.  Also, unit sometimes does not want to power up unless I unplug it and replug it.  Seems like a "software" problem rather than a physical problem (that is, I don't think that this is a bad connection at the plug, as that would not explain the refusal to accept commands).  Unit is 18 months old.  Still prints from computer on command (but, that is an instruction from the computer rather than human input via a button).  Ideas?  Thanks.