Hey Jason, I also have similar issues with 2.5. Here's my problem:
Notice the category box was empty but the category list was shown when clicking on "add new category". Also, the Advanced Options which should be below Category was missing. Any posts I publish are Comments Off.
It didnt appear to be plugin problems because:
1) I tried deactivating all plugins
2) I reverted back to the original php files that I made modifications too
3) It just happened without notice
4) I checked the MySQL database for errors
I wonder if lag was the problem. It was heavily lagged when I was writing posts and many times accessing the site timed out.
The last thing I want to do is to reinstall it and that's out of the question