I tested in both IE7 and Firefox 2.0.0.7
after I start website and request categories tree it doesn't work for a while, but eventually it start to work.
Maybe ASP.NET is compiling ashx component that supplies data for the tree, but the browser AJAX times out before compilation is finished - shows empty tree? once component is compiled it supplies data and the tree of categories is shown ok for all projects
btw, BugNet version got reset down to 7.0.0.0. not sure if that's by design. I upped it to 8.0.0.0 on my build.