Quicktime puzzle

[Rob Pitt]

My clinical decision support medical app has many quicktime clips. I am still using MC 2.3.2 and QT4 developing on MacOS 9. The clips have always played fine on W95/98/NT. Code is very simple
on mouseUp
  put GrphPath&"PPacMov/"&"neonacid.mov" into mvNmae
  play videoclip mvNmae at 220,250
end mouseUp 

I added two new QT clips as usual the other day and they run fine on MacOS, W95, W98 but they exhibited strange behaviour when the same CD was run on WindowsXP. The first frame shows momentarily then disappears and the movie plays its audio without any image at all. If you move the stack even a fraction sideways using the mouse the image comes back and the movie plays normally. I thought I would try QT6 player onto the XP machine and now most but (not all) movies exhibit this same behaviour .. even the ones that were behaving normally using QT4 player a few minutes before installing QT6.
Any one experienced this?
Any work around?
Any Metacard developers in this part of the world. My product goes to 100 hospitals in Australia and I need to update the interface .. as well as move to latest MC.

-- 
Assoc Prof Rob Pitt
Director Paediatric Emergency Medicine
Mater Childrens Hospital
Brisbane Qld Australia