Along with a long standing struggle to make a uniquely voiced follower that works with the current range of follower enhancement mods (can't quite work out to create a fully functioning follower script from scratch), I am struggling with another.

As we all know the actor face editing in the CK is not as user friendly or seemingly as detailed as that in the game. So I have attempted to use the SPF function to create NPC files of characters I want to build into what will be a fairly major mod. This has worked fine, but my CK crashes/freezes every time I try to import one. Yesterday I was able to import it once but only if I only loaded skyrim ESM and not into my ongoing mod file, and today it won't even do that.

Does anyone have any experience of this or suggestions?

This issue isn't specific to importing .npc files but affects any operation where you need to access the Windows directory, including trying to save a new mod for the first time. I use the SPF/import process all the time and the CK crashes on me about 2/3 to 3/4 of the time. I just work on two things at the same time, that way I can be productive while I'm waiting for the CK to load for the fourth time.