That appears to be a connection/network issue on your end -- are you using a proxy server and/or some third-party 'personal firewall'-type software by any chance? Also, have you looked at the troubleshooting section of the KVS Tool FAQ?
Am using Firewall however, have tried with firewall OFF and same behavior. (When the Firewall is enabled, its connection log feature does show a new local port opened at time of the click to look at the seatmap to 151.193.199.65:80 and 62bytes sent 0Bytes received).
Am I using a proxy server? No.
Have looked at the FAQ (and would suggest that it would be much easier for me to lreview the FAQ if it were on your website instead of or in addition to hard-to-read Flyertalk forum).
I don't think there is any more troubleshooting I can do without knowing what kind of URL/call the program is attempting.
UPDATE: I have tried with another [slow/dial-up] ISP and do not have the problem.
The ISP for my high-speed connection at present location does use
transparent proxy and
This article might give you some clues as to why KVS is not working with it (they use Squid). I, of course, have no control over my ISP's use of Squid, and in the location I am at do not have alternative ISP. I would imagine some KVS users in some locations (esp airports/public access places) may run into similar problems...?