I have experienced this portrait issue before myself and it seems to have something to do with the following options in the settings.txt file:
Code:
low_res_textures=no
force_pow2_textures=no
Basically, if you put one or both of these to yes it seems to break the portraits in some way. From what I've seen people seem to keep bumping into this problem from time to time, but putting the above options to no tends to solve the issue. Hope this helps, OP!