The update to Build 512 seems to have fixed the issue. I'm now able to switch between screens with no issues. I know this was the first time it's ever happened to me and I've been using BiaB since 2011. The behavior was so strange. I'm just glad it's taken care of (knock on wood). I sometimes write with BiaB and having to manually minimize the BiaB window to get to a lyric sheet on my computer was an extra step that got in the way (if only slightly) of the creative workflow.