Snail, please force refresh your browser window. Are recent topic titles from private boards you have no access to still visible to you?
If yes, go to your profile's Look and Layout Preferences, the first setting allows you to select forum theme (which has been enabled temporarily for testing purposes). Select SMF Default Theme. Does the problem still occur (please force refresh again)
This is going to annoy a boatload of people me included, but I had to reset theme settings for this. Please look at Look and Layout Preferences and set your preferences again if you had changed them. This includes everyone by the way.
Also, moving this to Site Support.