Ok, so I think I'm in the clear here.
I ran CCleaner and dumped a ton of registry issues (missing dlls, old junk, etc.) then I cleaned up the startup processes to only essential stuff.
I ran RAM tests and everything checked out alright, so I'm pretty sure something was just intercepting the processes, or causing hangs for other reasons.
I got some renders made again, and then the problem started resurrecting. I had to go turn off MP, start and cancel a render, then turn MP back on for things to work.
Even so.. there'd be extra AfterFX.exe processes running that would never go away, even after quitting AE.
Finally, sat down and took all my Tifs and just saved them as compressed JPG files.. (nothing horrible, but enough that they weren't tifs and they were smaller in file-size)
This didn't help the hang-ups, but it helped my render time a LITTLE when it did work..
then, I went through all of my video files, and was going to convert them all to a single codec (instead of all the strewn around delivery formats I received from the client.)
I was placing everything in my AME queue, and I noticed one of the video files wouldn't import.. it would hang AME.. so I opened it in QT and converted it out of there.
Turns out it was that file that was killing everything.. it was a file that I had originally converted to ProRes 444 from Cinec. it just wouldn't load in AME to convert, and once I converted it in QT and converted the rest of the video clips to the same format, everything has been butter.
seriously.. thanks for that suggestion.. I would never have expected it, considering AE never gave warning of the file having issue..
Also.. I went from about 30 minute render times for a 2 minute piece, down to 16:40 on my last test.. just from converting those Tifs and video clips alone.. I didn't even resize the tifs, just changed them to jpg format.
anyway.. Thanks a ton to all that chimed in.. seems I'm in good repair now. my "initializing background processes" message takes about 20 seconds before beginning the render, and I'm golden.
Cheers!