Not sure which Poser you use but in 7 you have control over texture res and transparency quality. This may need adjusting..(attached)

In P6 there were texture /memory load problems and it would refuse to add a new texture once it had cached too much. Only way to clear it was to reboot...

Then there is texture path. Perhaps you can point the exe installer to both your main runtime and externals.

Then there is doing the image file/ nodes yourself in the matroom. Easy to do. Study a similar prop hair and copy the settings... Then save the good Egypt hair back to your library so you never have to worry about it again. This is probably the best option