Just swapped out the PyFFied meshes BSAs and re-installed all NIFOpt BSAs, for more testing ..
Do you have the time to check with me that guy a while?
Well it was ALL NPCs (not just a few), both male and female - So before seeing your above post I had already decided to un-install all my body mod setup (un-installed Robert Male and EVE and all associated modifications to the game) ..
So with just vanilla files from the BSAs which have been processed through NIFOpt = No more head problems
http://www.bild.me/bild.php?file=3736887ScreenShot368.jpg
http://www.bild.me/bild.php?file=3406975ScreenShot369.jpg
Which means - I can successfully use NIFOpt'ed meshes with a vanilla setup, but need PyFFi'ed meshes for use with Body mods.
I guess then that maybe all body mod files could also be given the same NIFopt treatment, if they are to be used with NIFOpt'ed BSAs.
Scary thought, considering the body mod creators have various techniques to get the close to perfect skin tone etc with different layers, colour designated in the mesh, texture and normal map all of which NIFOpt may alter...
and non-standard paths to textures defined in the meshes (how does NIFOpt determine a path as non existant) to avoid shared male / female body resource problems, or just to distinguish them from other body mod parts by different authors, eye meshes too which pull in custom textures from custom locations (espless mods)
I haven't read NIFOpt documentation thoroughly yet, so the above are just thoughts generated from remembering parts of it I skimmed.
I remember also reading about NIFOpt stripping Parallax out of textures, is that right? - The reason I ask is I also remember from texture sets like CorePC's Vibrant collection of textures, that a lot of work was put into using Parallax to advantage. I dont again fully understand this side of texturing so maybe there is no need for alarm bells there. But maybe using NIFOpt on such texture sets would be removing aspects that should not be ... Although if the intent is to optimize then it could be desired, if the user understands what is being done to those textures and what difference it would mean in-game.
I just got the idea we may be able to use http://technet.microsoft.com/de-de/sysinternals/bb896645to see which NIF has been loaded last and then working through that list, which isn't very long I think. Otherwise we are (again) stuck ...
Sending you a PM, with a link to a couple of runs with ProcMon logs - I have filtered out all processes not necessary, so they include all Oblivion entries, and I also let one of windows processes remain in the list so you can see where the AppCrash event was ..
I did two runs, creating new log for each. To find the AppCrash event, have a look at log 2 (just turn off capturing, clear screen, then load my log) - Then go down to Time 12 06 49 - You will find a similar event in log 1 (I didn't note the time though, but it should be near the end of the log .. just have to scroll back up through all the close process events)
Hope that helps
Edit: I will keep this setup if you want any more runs with ProcMon (and any tips for filter Includes / Excludes you want me to run with)
Edit2: Also popped back to Leyawiin Mages guild to check out those windows again (now that I have all BSAs NIFOpt'ed back in the game) - Still have the same problem there, so I think we can conclude that problem is not a meshes problem, and possibly NIFOpt'ed texture related .