barton try creating a new character if it worked before, theres a chance your in a spot on the map your computer cant handle.
unfortunately lots of ppl are having the same problem at initialising world, so i cant really offer any advice except try the above, make sure you have the latest drivers, run the update patch, make sure you have no other programs running that may slow it down, and try to make it the first thing you load on your computer.
If none of that works come back here and see if anyone else can offer anything
