I came across this in the manual (and this is what I was thinking of when I mentioned the Network Rendering and IDL):  

 

**"Animation Considerations: When rendering out an **
**animation while using IDL, make sure that multi-threaded **
**rendering is not being used (set Number of Threads to 1 in **
**the Render tab of the General Preferences dialog). If you **
**leave the setting at 2 or higher, your renders will come out **
**jittery, as the shadows and lighting will not line up from **
**frame to frame."
 **

That seems ridiculous that you would have to cripple your render speed just to render IDL.  I'm going to render a short section with a single thread/cpu to see what happens.  I'm having a hard time believing this is it, although the description does seem to jive.  If that IS it, looks like I'll be going back to doing most of my renders in Vue.

If that isn't it (which I'm hoping) I'll post back with that info.  Thanks!