First of all i use Dreamweaver CS5.5 on Windows7 x64.
I remember that the first time i went to this detail page design and then it first show standard in the dropdown, i added some database columns to list below. Then i looked the other presets in the dropdown list starting from the top (int. adresses) or something. After looking some i choosed text only and the error message appears. After that i can choose any preset but the preview window never changes anymore. Also canceling this window and re-enter does not solve, i need to completely close DataAssist Page wizard and re-start.
Again sometimes i could choose, it seems to happen random but to be sure i'll have to test again tonight and see exact steps i did to get this error.