Area Lights rotate 90º for no reason

[roskilla23º]

Hello everyone, I really hope someone can help me out with this, as this is super annoying.....

I have a huge (around 2GB) C4D Project, with lots of animations going on but every light is fixed in place. What happens is that (sometimes) when I render using Bidir most of the area lights turn 90º and/or squeeze for no reason. So I have to delete them and create them again to solve the problem, but the following day I open the project and render the scene, I get the same error.

This is super super annoying. How can I rely on this renderer when I'm having such a problem? What if I send the whole animation to a render farm, spend more than a 100$ and find out that I have most of my lights rotated?

Hope someone knows how to solve this problem as I'm about to send it to the farm but I won't till I know everything works as it should.

EDIT. I'm rendering on a MacPro 3,5 GHz 6-Core Intel Xeon E5. Using CPU only with Bidir at 1080p.
THE PROBLEM DOES ALSO APPEAR WHEN NOT USING BIDIR.

[OnoSendai]

Are you using motion blur on the lights or any other objects?

[roskilla23º]

Yes, Everything is rendered with motion blur. The only object that is moving is the car and the wheels, the lights are fixed in place, no animation.

[roskilla23º]

Hey OnoSendai, any ideas how to solve the problem? I'm stuck to this point right now..

Thanks!!!

[OnoSendai]

Can you send us one frame of the animation as a PIGS? Thanks.
You can upload to dropbox etc.. and send a link via email.