Problems with Post Editor after upgrading to 2.8.x

I upgraded to 2.8 about a week after it was released, and I’ve had problems with the visual editor window ever since. If I switch to HTML view, I’m able to work with the post in that way. However, I’m much more of a “visual” type person so this isn’t working for me.

My symptoms:
– The text does’t show up. If I do a ctrl-a, it selects all of the text that I’ve entered, so it’s as if the editor window properties have been changed to show WHITE text.
– The toolbars are gone. I can work with media, but I can’t insert a page break, modify the alignment of the text, etc. All of those buttons are missing. They are perfectly visible on the HTML tab, though.

Has anyone else seen this? Any ideas on what happened? I upgraded to 2.8.1 today, and the problem still exists…