I hope by replying to this earlier post of Oct 9th, the most helpful observation in this stream, it can be high-lighted again.
As Ron states, find the "offending" COMMENTED code in the controlling CSS file, zap it out, save the file and, hey presto! Design view is back (albeit as part of a menu item shared with 'live') but you'll need to close and re-open your page. As the change is to a CSS any other pages under its control will have Design view when they are opened.
I found the spell-check available also.
Only downside that I've found is the 'grids' are gone in the work-space. And I've not yet created a fluid page from scratch again so maybe there will be a problem then??
As an aside, what I did was to create a duplicate of the CSS file, so that I could get back to it when Adobe sort the problem, before zapping the lines of code from the original.
Hope this helps and thanks again to Ron