Are you using a remote testing server? or a local one?
Using a remote testing server can cause the type of crashing you describe. With a remote testing server, the connection to the server can get lost by Dreamweaver. Data Assist will need to connect to the server while the pages are being created to get information about the table the pages are being created for.
it is recommended that you have a local testing server installed rather than use the remote server.
see the learning resources page for details on setting up a local testing server: