I think this is a bug with the vvvv rendering system. Essentially what I am seeing is that if you use multiple render targets your rendering disappears if you turn on anti-aliasing. I included a patch that should demonstrate this. Just turn on AA (and set it to anything other than None) in the first renderer and the results of the rendering in your second renderer will disappear.
This was reproed on 45beta26 running on Win7/x64 on a MacbookPro (NVidia GeForce GT 330M).
Patch that demonstrates bug (5.3 kB)