ImageMagick hangs on Windows when converting large PDF to PNG

Hi,

I am trying to use ImageMagick to convert a large number of PDFs to PNGs on
Windows (XP). When attempting to convert one particularly large PDF (note
large dimension-wise, not file-size-wise), ImageMagick seems to hang. I can
see in the process list in task manager, convert.exe, is taking large
amounts of CPU time/memory initially, then "slowing down" and using less
memory/CPU, but never exiting, and causing the computer itself to run
extremely slow. I then kill the process, which also leaves what appear to be
temporary files in "C:\", some larger than 500MB. This problem doesn't seem
to exist on Linux, as I have the same version of ImageMagick installed on
one of my Ubuntu boxes, and it performs the conversion in a timely manner. I
am fully aware that ImageMagick is using ghostscript to convert the PDF, but
I don't see it in the process list, and I am also unsure as to how
ImageMagick interacts with ghostscript to perform the conversion. I am using
ImageMagick version 6.6.1-7 with ghostscript version 8.71, with command line
flags `-density 150 and -resize 2000`. Ghostscript is the same version on my
Linux machine as well. This is the pdf in question:
http://24.187.210.198/other/big.pdf

Thanks,
-Ryan Kelly