Shadow errors and flashing walls when approaching

So, I have noticed a problem with the lighting in my map. In the game the map is always in more of a dim kind of light, however when at a distance, this happens:

As you can see, the shadows dissolve into a bunch of lines when the light is moved a considerable distance away from the walls. However, when I move closer:

The area is now decently lit.
It is also worth mentioning that whenever a wall facing the player is lit up from a distance, the wall continues to violently flash as the player moves closer to it. they do not flash when the player is still. In my opinion, this is a bigger problem than the shadows. Any help is appreciated.