Wow...your system sure shouldn't be the problem. I've never rendered anything that large, but just for the heck of it, as I'm typing this, I have a 4000x4000x200dpi render going of a fairly simple scene...the PWFW bedroom with Vic2 and Mike 2---dressed and textured. It seems to be going fine... Did you try to clear out all your temp files, etc ??? defrag your hard drive? Sorry to go here, but I just went through some major problems with temp files---had to go into the registry to clean them up...my system was at a crawl....could barely read my email....finally got those temp files deleted...all is working to par again. Well..its done..and it worked..61meg tiff file...huge :)

Humankind has not woven the web of life. We are but one thread within it.
Whatever we do to the web, we do to ourselves. All things are bound together.
All things connect......Chief Seattle, 1854