trying to get a motion menu going

loaded mpeg into tscv
created chapters every 6 minutes
clicked on "menu generator"
positioned chapters where i want on X & Y axis
set thumbnail size to 125 x 100
set 200 frames to appear [approx 6secs]

then this is where it gets funny
when i click on "create menu" in does the first 5 chapters fine
then the last 3 chapters FREEZE UP and have 0 motion to them

everything else goes fine except the last few chapters

is this happening because of a dropped frame or something in the source .mpg ?

plz reply