Select a file in your project that you know has lots of commits and at least one branch.
right-click | CVS | Show History
Using your up and down arrow keys, you can scroll through and the "Commit Message" updates properly.
Now push the "Show As Tree" button (the view will re-sort). Now... using the up/down arrow keys, all the commit messages are off by one. That is: on your first 'up' keystroke, the message doesn't change (it's still showing the previous message). Then you hit 'up' again, and you get the previous one, etc, etc.
Clicking each row with your mouse, does result in the correct message being shown, but using the arrow keys, it is one behind.
For reference, tried asking here, but no response: http://www.intellij.net/forums/thread.jspa?threadID=275488&tstart=15