Something you could try would be to turn down your graphics settings before you fast travel (internal and external shadows and spectral effects all the way to the left on the slider. Shadow filter off and view distance set to minimum). I've had this problem in the past, and reducing the graphic settings before fast travel allowed me to continue with the game. If it works, once you get to your destination you should be able to safely restore your graphic settings to the way you want them. When you are having this type of problem it is really important to save a lot (I'm sure you already know that).
One last observation, when I was having this problem it was due to Natural
Environments/Natural Weather being installed.
Good luck.