Since I have upgraded to Windows XP, connecting to chessclub.com seems erratic. how come ?

This is caused by the universal plug and play service. This service is enabled by default and is using port 5000. Workaround is to disable the UPNP service or use port 5001 to connect to chessclub.com. On freechess.org port 23 seems to work. For more background information and instruction how to disable UPNP see here...