I just upgraded to XCode 4 and am now unable to view a number of my previous XCode 3 projects. When I launch the projects XCode opens, but it looks like this:

Any way to tell what is going wrong? Any special logs I can look at? I don’t get any warnings or errors appearing!
The solution was to delete the local project files and re-clone from the GIT repository. Not sure what the issue is, but it may have been related to having opened the project in XCode 4 Developer Preview.