The address 239.255.255.250 is positifly not an an Internet host. If you you have
a personal firewall and configured it to block and log incoming ICMPs then ping this
address and watch the log. Voila this is your machine, isn't it? In fact this is
an IP multicast address. IP multicast addresses can range from 224.0.0.0 to 239.255.255.255.
The address 239.255.255.250 seems to be the multicast localhost adress in XP.