You are using Poser9? Correct?

Poser9 is a 32 bit application.. Putting more RAM in your system will not help.

But yes, Poser9 does have a transparancy problem that is being worked on.
Should be OK when the SR's come out.

So far, I just connect the texture to diffuse color white, set the diffuse value at 0.8, and also connect the same texture to Bump at 0.5 and Displacement at 0.1
(Poser units in inches)

But?
Even Poser9 should not choke with one figure and one transmapped hair.

Please, unless absolutely required. Forget IBL. Like AO, it is fake and from a period before IDL.

Use bb's sphere and render with IDL.

I always use bb's sphere and ONE (1) infinite light. '(That often has to be reduced to 60% because you have too mush light  :-) :-) in your scene.

The cases I use a second light became from rare, to extremely rare, to well, it has been weeks now. :-)

I prefer to use ambient on the objects that have a natural glow like a TV screen, a PC screen, a lightbulb, a candle.

Sometimes, in an enclosed environment like a room, it helps to put a little ambient on the walls and cieling too. I use ambient on close to every cieling.

I think with your RAM, you need an system clean up. (You did not mention your CPU)
I would download Advanced System Care free, from iobit, and let it do its Deep cleaning. (Version 4.2 now)

Or Glary Utilities
Or Winutilities

All free and pretty good in housekeeping.
just let them do their thing.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!