This seems to be the never ending "problem" on WinXP and even now on Vista across several versions of CN.
It starts uploading, after some time it simply stops doing that and disconnects (Disconnected in bottom left side).
Both ends (server and client) should have option to auto-reconnect on disconnect and also auto-retrasnfer so it will (re)start (or resume if transfer was already done before) sending data as soon as both can see eachother (now the recieving party has to constantly montor CN to see if it disconnects and resume the download). Thats super annoying and makes CN completelly useless.

Hi,

This disconnection problem is highly acute during p2p transfer modes because transfers between residential ISPs is highly congested and latency prone. Unlike publicly shared content with systems like Bittorrent, privately shared content through Netizen is not replicated across other peers, resulting in higher disruption rates. I've been tweaking the networking stack to compensate for such things and will be including it in the next release. We are also adding a centralized hosting service to help alleviate this problem.

There is no need to constantly monitor Netizen for transfers. It has a built in retry timer that automatically reconnects to the network and resume downloads. I've tweaked the resume timer to be more aggressive for the next release so that it triggers retries more frequently.

I apologize for the inconvenience. Still working hard to fix these problems.