Upgrade went smoothly, except for a small login error and a couple minor plug-in errors.  I Google’ d it like usual, and came across this blog site that had the EXACT same errors I had:
http://konstruktors.com/blog/wordpress/169-solving-authentication-and-plugin-errors-after-upgrade-to-wordpress-2-5/
“You do not have sufficient permissions to access this page” after Admin login, and also the fatal error on activating the […]

Popularity: 100% [?]