Disappearing hair during the render?

Hello!
I found some strange render effects: After 65 frames the hair of V6 disappeared until frame 85. Onf rame 86 it appears again.
I attached 2 screenshots.
I already rebuild the database and rebooted the system. The error can be reproduced.
Someone has an explaination for this?
Thank you!
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silke065.jpg
1000 x 671 - 286K
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silke064.jpg
1000 x 671 - 286K
Post edited by Fetito on
Comments
Addendum:
I added a YouTube-video to illustrate this issue: http://www.youtube.com/watch?v=0Edm5rLyOMI&feature=youtu.be
Have you Checked the Timeline for a Key frame that has the Item set to Display in Render Off? And then another for it to return? Check that first.