Don’t know if this will help or if I just got lucky, but I did you happen to install WP manually?
I had similar problems and problems with uploading avatars on WP when I used Fantastico, that I wasn’t having on a WPMU installation. Out of curiosity I installed the single WP directly, and I no longer have problems with seeing my profile or avatars. Then again, you’d have to have a fresh install, which I know isn’t possible for everyone to do, but at least for me it solved the problem.
Nothing against Fantastico, but I had similar problems when I’d used it for a Drupal site. Lots of errors with some modules that dissapeared when I installed manually.