Sorry if this bug was reported before but I coudn't find anything similar.
The problem is this; I was trying out the 1st tutorial and, when I click on "run layout" this happends.
<img src="http://img16.imageshack.us/img16/9584/todoslosasset.jpg" border="0">
I tried it in chrome and it works fine. The problem seems to be in firefox 4.
Either way, here's the url if you want to try it yourselves here
Tell me if you need the project file.
bye and thanks!