From what you describe, it doesn't seem to be a hang caused by this.
With your amount of memory, you shouldn't even have a HIGHMEM segment,
which makes bugs even less likely. So I don't know what happened to
your system, or if you're doing something wrong or not. I've just
installed a Hurd system on a VM myself, and I had paging problems
when upgrading from the snapshot to unstable, but once I assigned 2g
of RAM, I could upgrade without too much trouble with aptitude. I
use it on all my machines, Linux and Hurd, and never have such issues.