Most likely there is some access restriction at the switch management level:
Take a look at the procurve manual:
HP ProCurve Switches 1600m, 2424m, 4000m, and 8000m
Pg. 97 and 98 of the manual talks about SNMP access.
"This feature does not affect SNMP access to the switch by SNMP-authorized management stations. (SNMP access is protected by community names and an independent SNMP Authorized Managers list.)"
"Authorizing Single Stations: The table entry authorizes a single management station to have IP access to the switch. To use this method, just enter the IP address of an authorized management station in the Authorized Manager IP column, and leave the IP Mask set to 255.255.255.255. This is the easiest way to use the Authorized Managers feature. "
Please, try to add the IP address of the NetCrunch server to the list of SNMP-authorized management stations.
