Originally Posted by
shadowx360
There are actually several locations that store your XUID, which is actually the result of a hash function, and it is an array of 4 bytes represented in hex. One location stores what you see in the console when you open the game. Servers check your XUID when you first join the server, and then some other crap happens that I never bothered to check out, but basically my sniffer catches my XUID being sent to the server pretty often, periodically. Anyways, a constant holding your XUID is sent to the server every so often, and if you are banned, you get a steam auth error, instead of a "you're banned" error.
As for where the LSP error is stored, it's useless to know. If you're trying to unban yourself from that angle, I suggest you stop trying. Been there, done that.
As for changing your XUID ingame, that's changing your XUID after the game has started.