If you don't want to bother with re-entering all your other changes... Run XoloX while you are disconnected from the network (not dialed up, up with ethernet card unplugged from cable/DSL modem) and llet it run out of hosts to try. It'll pop up a box asking if you want to change your settings.

IF yoru current proxy information is invalid, are you still able to conenct to the network? Or were you just wondering in a general way because you might have to change the options in the future?