I'm having the same problem with Natty and Deluge (Client Version: 1.3.2
Libtorrent Version: 0.15.6.0, same with Transmission).

I'm downloading the file to my windows partition on the same disk and it seems, prima facie, to be working as normal. File is 6.3GBs, same happens with a 14GB file. All the symptoms as above- stops downloading immediately, try to close crashed Deluge, xkill the window yet the process remains as zombie taking 100% of my puny netbook CPU. Only restart fixes.

I would request anyone's help as this isn't on- I had to restart my netbook a dozen times trying all the above suggestions to no avail.... I mean restart my netbook like a windows machine for goodness sake!

Help please!