To reproduce: 1. Go to http://build.webkit.org/LeaksViewer/?url=http://build.webkit.org/results/SnowLeopard%20Intel%20Leaks/r80699%20(15461)/DumpRenderTree-leaks.txt Leaks Viewer will say it's loading forever. What has actually happened is an exception was thrown while loading the leaks data (bug 56090). We should notice when this happens and stop claiming to be loading (and tell the user).
Oh, the error doesn't happen in ToT, only in Safari 5.