cnc pro "skipping" blocks

Hi Guys
Anyone have an occasional hiccup with cncpro where it blows right
by a line of code? It has happened to me several times[remember the
old thread about dos and math errors?]
I had a talk with another guy today who experiences same thing.When
it happens it is always the at same line. Usually the last Z up
command at end of program!
Happened to me the other day so I played with all the likely suspects
in cfg file,feed speeds,accel, etc. Nothing helped.
Finally I put another [redundant] line of code just before the
problem line and voila! File ran several times no problem.

Carl