If the DR (or any other part of the realm) is stupidly dark, then perhaps you need to relight that particular map. In your PS setup application (for windoze users it's in the PS Crystal Blue menu folder) there is a Relight Maps option, where you can select a map to relight.
There is probably an easier way than this, but to find out which map you're in, Unstick yourself (/unstick) and it'll say "Moving back to a valid position in [mapname]"
*Warning* though, the relighting process can take a while.