I just wanted to let you know that I found the source.squeakfoundation.org SqueakSource image locked up pegging the CPU. I had it running under VNC so I could at least see it although I could not interact. There was a debugger up and the transcript was marked out as undrawable. Perhaps leaving transcript open is not a good idea. I killed and restarted the image and closed the transcript along with most of the other windows.
Ken