Stereo 3D stops working depending on camera position/lookat

[lulzfish]

I'm using nvidia's "3D Vision" to do stereoscopic 3D. Irrlicht seems to have built-in support for this.

Here's the code:
http://pastebin.com/9s4gEZuX

On line 24, the camera's position and lookat vectors have the same Z, causing this effect:
http://imgur.com/ytdLg

Changing the lookat's Z from 10 to 10.01 causes the stereo 3d to suddenly start working again:
http://imgur.com/2Be77

Here it is with multiple objects:
http://imgur.com/X0Fau
http://imgur.com/dROje

My team noticed this in a different Irrlicht program, where some objects were in 3D, and some were not, depending on the camera position.
I have not been able to duplicate that. In my tests, either all or none of the objects are in 3D.

As far as I can tell, it never happens with FPS cameras, so for now I'll try to use them instead.
Edit: In the main program (not the one I posted) the problem does occur with FPS cameras.

Edit: It seems that rotating a node makes the 3D work properly.

[hybrid]

Hmm, not sure where to search for this bug now. Looks more like a precision error or some wrong setup of some matrices, which are updated at rotation (which FPS cam also does automatically).