Just looking for an update on this. Currently it is not possible to use VNC Manager to scan for Windows XP Pro SP2 workstations. You have to manually create and maintain these entries. Everything else seems to work fine. The last  status from you was that this is a know issue, not unique to VNC Manager, and that noone had been able to figure out why this was happening. What's the current status?

Thanks.

I think we actually posted to our old forum some explanations for this problem.
The following change in SP2 has broken all network scanners and VNC Manager's too:

Detailed description

The TCP/IP stack now limits the number of simultaneous incomplete outbound TCP connection attempts. After the limit has been reached, subsequent connection attempts are put in a queue and will be resolved at a fixed rate. Under normal operation, when applications are connecting to available hosts at valid IP addresses, no connection rate-limiting will occur. When it does occur, a new event, with ID 4226, appears in the system’s event log.

The only workaround to this problem available is to install modified version of tcpip.sys driver, which have this limitation removed. For obvious reasons we won't host this file on our web site. But it's easy to find one using any search engine.