I found the reason but I'm not very happy about it.
Windows XP IIS has a 10 concurrent user limit.
I can only assume that each page called for is making another conection.
This can be fixed partially via the support document above but still a ten user limit will apply.
With the HTTP KeepAlives disabled I what does a user connection mean?
Does this mean ten sessions?
They say, best men are moulded out of faults,
And, for the most, become much more the better
For being a little bad.