the old procurve has a nice security feature, you can define a management port. only if your are connected to this port, you can access the webinterface.
if your self written documentation says you have used port 2 as managment port and your memory tells you, you have no specific managment port configured but your browser can't connect to the webinterface. how to debug the that?
it has cost me sime time but sometimes it is not your fault, sometimes only the webserver of the switch crashed.
a simple reboot of your switch solves the problem :)