I'm following this tutorial (http://www.lucasforums.com/showthread.php?t=193050).

I'm following it step by step (except for using bastila and the name, since it's not bastila's head) and when I open up the replacer, I can replace the .mdl file, but the .mdx I have a problem with... this is what pops up when I try to save a new .mdx file...

http://i1138.photobucket.com/albums/n530/deathknightlupin/error.png)

which model are you using?

I was using the Male Blond PC however, I attempted it with nearly every other head and I still got the same error. :/

do you have a screenshot of Taina's with all the boxes that you have checked?

I know that certain models have problems loading in gmax (PMHA06, PMHA08, PMHB06 & PMHC06 are examples). I seem to remember that they also have problems with Taina's replacer.

I do not, but I can tell you which boxes I had checked. g_head (or the one that represents the head in general lol), head and then hair_front.

This problem has come up a few times. Try looking through some of the other threads about it (I used the search feature for these):
http://www.lucasforums.com/search.php?searchid=412659)

One you'll come accross is this one where I had the same problem
http://www.lucasforums.com/showthread.php?t=196415&highlight=Taina%27s+error)
I never did get if figured out for the Twi'lek male head model, and I can't remember if I ever solved it for any other time either. Sorry.

This might help:
http://www.lucasforums.com/showthread.php?t=196570&highlight=Taina%27s+Access+Violation)