> "title" Title to display in window title bar.
I knew this..... for some degrees

if MP4.BAT had below and was singlely executed
either
START "%P2%" %1
or
START "" "%P2%" %1
worked or they caused no troubles.


but if MP4.BAT had
c:\zzz\video.bat %1
and video.bat was the one that had the program
START "%P2%" %1 --> caused PC to crash due to fall into an endless loop (visible flickerings)
START "" "%P2%" %1 --> worked.

dealing with start.exe crashing never happened to me before, it came as a shock.
after this thread, I feel better. thanks