As part of my learning process, I have some useful open sourced code that I collected for reference and compiled in the previous xcode and sdk (3.1). I know where to edit my base SDK settings (4.0) in Project Settings.
There is one project, where when I compile and launch in Simulator it comes up as a black screen. My first thought was delete the build folder, and then run and build. No dice, next was checking the View Controller and File Owner settings in Interface Builder. That appears correct, so I'm stumped.
I'm thinking if I go back to 3.2.2 and re-compile it in 3.1, then I can have something to compare. So, I'm trying to rule that out, actually avoid uninstalling Xcode 3.2.3 as a troubleshooting method.