AutoCAD Inventor :: Solid / Visible Parts Showing Up As Hidden Lines On IDW

I'm having issues involving hidden lines that should not be hidden lines in the idw environment. 

I am using Inventor 2010 suite, 64-bit.  I have  largish assembly modeled with several sub-assemblies and a few reference assemblies.   Some of the reference models are shrinkwraps from other large assemblies (surface type shrinkwrap, link broken), and other reference models are acutal assemblies that I am unable to shrinkwrap because I need the positional reps that they provide.

When I place my parent assembly, with all the normal and reference models included, on an idw, large portions of the reference models do not show up.  If I change my line style to show hidden lines, the missing parts show up.  At first, I thought that it may be because the reference parts in question were not originally in the view due to the reference data margin, so I started a new sheet and set the margin large enough to show the entire machine, as well as the state of Michigan, before I set the base view, but I still don't get those parts unless I enable hidden lines.

Even at that, Inventor is not behaving consistently.  Some of the parts that won't show unless hidden lines enabled are fabricated  parts that I or a co-worker modeled, some of the parts were imported from SAT, STEP and IGES files, and some of them are shrinkwrap parts.  On top of that, some of the parts will show up normal (without hidden lines shown) if I change the part's BOM structure from reference to normal, while others still will not show unless hidden lines are enabled, regardless of the BOM structure.  Keep in mind, none of these parts are hidden behind anything in the model, even with everything visible in my design view rep, so what's causing Inventor to think these parts are hidden.

Computer Specs:
Dell Precision M6500 mobile workstation (purchased in April 2010)
Windows 7, 64 bit OS
Intel i7 processor
8 GB RAM
NVIDIA Quadro FX 2800M graphics
Inventor Suite 2010, Subscription Advantage Pack, SP3
 
Computer Specs:
Dell Precision M6500 mobile workstation
Windows 7 SP1, 64 bit OS
Intel i7 processor
12 GB RAM
NVIDIA Quadro FX 2800M graphics
Inventor Suite 2010, Subscription Advantage Pack, SP4