We are experiencing the same issue with PDF or printer. Please email if a solution exists to insert editable (and printable) object, beyond copying into Mathcad as the other user has posted. Thankyou!
I had this issue but it is no longer reproduced after installing Office 2007 SP2. It seems bug is with Excel not Mathcad
I had this same problem with M14 and only found 1 solution.
I used the advanced editing tool-up tool in Acrobat. Selected the clack object and hit delete. This removed the black image.
Horrible, but worked.