Burntleaf, that loading screen is when you change maps (from Hydlaa Plaza to Hydlaa Sewers, Hydlaa Plaza to Arena, etc) It\'s loading the map for that area, it just uses the same background picture because they haven\'t yet made \"Loading (insert location name here)\" images.
As for the flashing, I\'ve experienced that in the forest when the shading changes (I guess there are issues with the lighting algorithm or whatnot). It only flashes briefly when I enter and exit the forest and looks like it\'s trying to render a lightening storm ^_^; I don\'t believe this is the same thing, though. What I was experiencing was a bottleneck on account of my video card.
edit: It flashes in the forest, and in the Pub. Both instances involve chaging the shading, so I guess it\'s something funky with whatever algorithms take care of shadows/shading.
~Indi