curious labs has a memory updater [download page] for 4.03 and propack (which is supposedly for >2g mem). Don't know if it really worked but have not had same problems as you with win98SE, 512m, and the memory updaters installed. I also use quite a bit of harddrive dedicated to virtual memory. My usual renders are around 500 frames of animation on average and MSOutlook blue screens me more than P4 w/propack.