Try doing a complete refresh of the page. Press and hold ctrl and click the refresh button, if you are using Intenet Explorer. For firefox press and hold shift and click the refresh button. This forces the browser to get the page from the server instead of the cache.
I had the same problem (in Falleen), used the refresh solution mentioned above, but still can't move south. The screen just refreshes to the first room I was in, either the entry room, or the shipwright room.