I have a similar problem. Also stuck at 95%. When I waited for a long time, I finally got a crash with “out of mem” error (I Have 8GB RAM on Win7 64)
I increased page file size and am trying again. My CPU and RAM usage is at 100%, which I hardly ever (or never) see.
Is there a “pre-compiled” version of the demo which does not require all this, some kind of standalone? I remember that when the Boy and His Kite demo appeared, somewhere on the internet I found a link to the demo with an exe file which would just run immediately on its own. I hope same can be done for the Infiltrator demo.