Just to toss in my IT-Drone .02 here:

As people have repeatedly said, 10053s are very difficult to deal with because the error message itself means almost nothing vis-a-vis the actual problem. It's a bit like getting robbed and then finding out that the culprit lives in Los Angeles; a start, but not particularly helpful.

At its core though, a 10053 is typically just a connection stability issue, and most of them that I've ever encountered, except, of course, the instance I'm trying to solve now, can be dealt with by doing one of a couple of things (preferably both):

1) If you're behind a router, take all of the machines on your LAN off of the DHCP table (just be sure to leave the service on so that you can use your router's LAN IP as a backup DNS). Why? Because DHCP can be, well, a little finicky in the stability department. Plus, it takes a bit of the load off of the router itself since it no longer has to 'decide' how to handle the connections from the PCs on the network.

2) Optimize your TCP/IP settings for your connection type. The reason for this one is simple. The Windows default TCP/IP settings are designed to work with either very low-speed connections (dial-up) or very low-latency connections (ethernet LANs, for instance). Particularly with XP (and especially with XP Pro, due it being designed to run on professionally maintained networks), the super-low-latency defaults can play havoc with persistent connections (read: connections that are allowed to idle) over the internet-at-large. An optimization will take care of it.

Anyway, just thought I'd toss a couple of additional solutions into the mix in the hopes that they help somebody. Good luck to all you folks having problems out there.

Disclaimer: There is no guarantee that doing either of these things will totally resolve the issue, but they will almost certainly reduce its frequency. Also, manually configuring your DNS/Gateway/Subnet/etc. is a relatively safe thing to do, even for a novice (just go back to autodetect if you mis-configure it). Messing with TCP/IP is not. Do NOT do it manually unless you know what you're doing. There are numerous free programs out there that will do a relatively good job of optimizing those settings for you with minimal risk and full backup/restore functionality. Use one of those.