I'm not sure if this is a server/network issue or something dodgy on this one workstation.
I have been having intermittent slow network access for some time, and have tried various things at various times, but haven't really got to the problem. Now I've started getting this NetBT error 4321 and HTTP does not seem to work (I can still access websites using HTTPS). In the error message in the event log it is saying that the name could not be registered, but the name it gives does not appear to be the correct computer name. It is showing the domain name a couple of spaces then :1d, which looks to me like it's got a corruption of the name somewhere.
We were doing some work on the server on Friday to fix some problems, and it's possible that this has somehow caused this, although it was working fine on Monday, and only started getting the problem on Tuesday. I think the machine may have been left on over the weekend so it was probably after re-booting. Most of the changes we made were to fix some startup problems on the server, so I don't think this would affect it. We did make some changes though to the group policy firewall settings though which were preventing remote access to XP machines, and we were using this machine to investigate and test this, so it's possible that we inadvertenly changed a setting somewhere.
Any suggestions where to start looking?