ah HAH! that is, in fact, what I'm using.
My D drive.
Since it (the error) referenced Virtual Memory, which is slightly odd as I have 32 GB of DDR4, my memory usage never got above like 45% or so, I removed the page file from the C drive and added it to the E drive and set it to 100GB. It's made quite the difference in my Tower toon's performance, but it didn't seem to have any affect whatsoever with the L2net IG, which I also thought was odd. why would it affect one but not the other?
Anyway, once I reach a stopping point, I'll go log out one of my toons and log it in with L2net IG, let it die, and post the error it throws. Maybe I'm missing something?