if it's still off, then that wasn't it.
I've tried with FF 8.0, and IE 9, with the same results. Access through proxify.com works, as that too filters the rst flag.
Apparently wrong headers (or similar) serverside might trigger rst for some reason.
I seem to remember something like that regarding a wordpress update a long while ago on a couple of other sites (they work now though).
No idea how to avoid it on my side except maybe install a nonMS firewall or something.
Btw, no proxy. Just a netgear wnr3500l router which I've never had any issues with..