Good point Chris, sorry about that, thought this was a Lightroom bug reporting blog. I'm using Lightroom 4, noticed the flashes durnig the Beta upload and thought they would disappear when purchased the full version. Have been using Lightroom since it was a beta test before version 1 hit the market and haven't had this issue before. In fact, just booted up Lightroom 3 and had no issue when I used adjustment brush. Is it possible that my video card is having conflict with only Lightroom 4? Thanks for any help or ideas.