It isn't a subtle problem, just an obscure one.

Navigate to and from that page in IE while watching memory. If memory usage goes up rapidly, you probably have the problem that I was referring to. Or even more simply, if you can submit from that page back to itself, just hit submit a bunch of times while watching memory.

Particularly if the page has a lot on it, IE's representation of the page takes up a lot of memory. (If you didn't have a lot on it to start with, you can arrange to...) Leaking 10 MB at a time very quickly becomes noticable.

Cheers,
Ben