hairfx n vray problem

[filmaka]

hi guys,
hope you can help me
i have got the problem, that around frame 85 in my animation my hairfx-hair disappears.it seems to render fine with scanline or if the camera is not animated.any ideas?
leszek

[filmaka]

ok.little more details.
the hair seems to render untill the first key of the camera,
then at this key it suddenly disappears.more odd is that with
motionblur on, the hair fades out slowly before it is gone.?!
do only i have this problem?
help really appreciated!vlado?anyone?
greets
leszek