I am in no way a "HP-UX master", but this sounds suspiciously like a resolution problem. Most times when the system is fine but network response is infinitely bad it is for one of two reasons:

1) The DNS server you are using responds very slowly (or not at all). This might come from a severed link between the two machines (for instance a firewall blocking port 53) or whatever. Have a look at /etc/nsswitch, "files" should go before "bind", meaning name resolution first tries a local /etc/hosts file and only then the DNS server. You might want to put all the "important" systems into /etc/hosts so that you do not have to rely on DNS being available.

2) Another possible scenario would be a "physically" severed link to the network. Possible causes would be a switch port set to half-duplex while the system port is set to full-duplex (or vice versa), different link speeds, Auto-Negotiation gone awry, or similar. Half-duplex vs full-duplex is tricky because "ping" will work (most of the time, anyways) but the line speed will be reduced to near zilch.

I hope this helps.

bakunin