I run IIS, exactly the same as Microsoft's (Well, Akamaiaiaiaimaimaia, or however you spell it) servers.
I'll do some playing and research - I wonder if the filename length has anything to do with this too.. the filename is pretty long, maybe that triggers it, if its over 4gb, maybe a buffer overflow in NTL's proxies?
Edit: You're definately right - it is the content length which handles it (The reason it appeared to change is because in order to then get the right file, i changed the content type which it then tried to resume, requesting on from where i had got too (about 2mb) -> EOF - which meant it was under the 32bit filesize limit, and would then work. If you have a download manager, you can always try downloading the first 2mb or so, pausing, then resuming - see if it then wakes up and gets the right filesize
-Liam