I had this funny problem after upgrading to WP 2.8.4 (from 2.6.5 via 2.7.1):
When trying to edit one particular post, instead of a normal edit panel with editable text, the browser went totally white.
After disabling all plugins it appeared, but only in html - even in "visual" view. Even more strange was that NONE of the buttons or dropdown panels worked.
I solved the problem by copying the html to an editor before deleting the post (that worked!) and then making a new one. But anyway:
What could be the reason for this problem?
With the new post everything worked as normal, also with all the plugins reactivated.
Trouble-post here (lots of content to loose...)