I also have the latest build and Windows XP SP2, but Home not Pro. I have one Page File 2046 Mb. And 2Gb RAM. The two pz3s I loaded are both about 66 Mb in size, so it was a much higher load than your figures. The higher the resource load, the more rapid is the decay just from ordinary moves.

You still lost resources deleting figures; you went from 63% with your two figures down to 34%. Try getting back to 63%.