It happens to all my active downloads, and I only download videos mainly so I can't really tell you if it affects other downloads. I'm running 10.5 leopard and I've got the latest Java update installed. They don't stall, they just sit there and do nothing, but either state that they're at 0kb/s or at another kb/s, but the amount downloaded stays the same, no matter how long I leave it opened for. I have tried searching for the file again, but doesn't work.