Whenever I go into a dugeon with light sources from candles or torches or anything that gives off light, wierd things are starting to happen. The light sources turn on and off and also affect my framerate. Also the shadow striping is worse than it's ever been even with the Shadow Striping Fix mod. What's going on?

Please see my vid below, does this match your problem? I was advised that the cause was a failing gpu, however the problem persists after physically removing the component. Sorry for the rubbish footage btw.
http://www.youtube.com/watch?v=2b4cXcIwgP0