Inserted wmv movie causing PowerPoint presentatio freeze!!!!

Please help!
I have 10 .wmv movies inserted in presentation, all on different 10 slides,
(transition is set up on a click). Everything plays normal in PowerPoint
2003, but in 2007 when playing slide #7 and clicking to go to the next slide
causing the presentation to crush. I have Windows XP, WMP version 11. I
tryied on a computer with Window VIsta, PowerPoint 2007 and it freezes the
slide before the end of the movie. I spent some time on this, and I noticed,
that the bit rate of the movie 1-7 is lower than movie 8-10. Could that be a
problem in PowerPoint 2007? Also, I've changed the slides around and it
actually looks that going from slide with a lover bit rate movie to a slide
with higher bit rate causing the problem. But this may be just a coincident.
Could anyone help me with this?