If you're putting in the port number, bypassing nsvhr and nsunix and still seeing this problem, well, pardon me, but I'll first breathe a sigh of relief (I've received two other nsvhr/POST reports in the past 24 hours....)
But do make sure you are putting in the port number, as this report sounds very much like the problem I just fixed.
Regarding simulating POSTs, what I usually do is use AOLserver and the ACS itself. The ACS contains a utility, util_httppost which can be used to POST to another webserver. What you can do is set up AOLserver on the machine you want to test "from", connect to the nscp port, and then in that tcl shell, use util_httppost to create a POST from the test machine to your target machine.
Since you are using my AOLserver patches, you can experiment with turning DEBUG on and DEV on within your config.tcl's ns/parameters section. This should cause most every byte sent or received from your AOLserver process to be dumped out in HEXL (HEX and ASCII) format in your server log, and that can help you catch the problem, and determine if it is AOLserver that is dropping the ball, and if so, where.
