before using Power CMS, there are a few things that you will need to have in place:
1) you need to properly define your dreamweaver site for dynamic development. see the "Defining a Dynamic Site in Dreamweaver" tutorial on the learning resources page:
2) Create a database connection, see the "Creating your database connection in Dreamweaver" tutorial on the learning resources page.
3) Create a new php page and save it to your dreamweaver site.
with the new php page open , you can use power CMS Builder.
for the error you are getting, go to Window -> Workspace layouts -> Reset '<your layout name>'