All the usual ones. You could very well hose your image. The nice thing, though, is that you could just kill your process, restart the image, and recover all of your code changes.
You could also have a Smalltalk "Process" (or green thread) starve the other ones. Lots of Smalltalks are single-threaded. VisualWorks is too, but has tricks for calling out to DLLs with a separate thread.
