Have been playing for a while and have been slowly working my way across the map from NE to SW - now that I am in the DC area proper I have entered the national Mall. I have visited all locations there (all map shortcuts) like The mall NW, The Mall NE, Museum Station, Washington Monument, Museum of Technology, Museum of History and National Archives. Then I started making my way towards the Capitiol Building.
I cannot approach it - every time I move in that general direction, I get a CTD. No error, no message, nothing.

I am curious - has anyone experienced the same thing or a similar event and is there a way to solve it (or bypass).
Now, since I cannot approach the Capitol Building I can't get the shortcut on the map and thus not fast travel there.

Any thoughts are appreciated

There's a back door to the Capitol in Seward Square and you can work your way to the front door. That might be worth a shot. You can reach Seward from Anacostia Station next to Rivet City.