btw,
You can "fix" it by having another ship join the CTD fleet. Select something other then that fleet, and it should reset it. For a while anyway, ETW still need a few seconds to sort itself out every time you select that fleet and will CTD eventually.
I have a sloop tailing my battle fleet now. Aside from having a fix for the CTD issue close by, it's a rather nice enemy fleet magnet, drawing in your main fleet.