It's not crashing when I try to load a game, but when I click to switch over from the normal scenarios to where all the saves are listed. I don't remember marking a character as being of interest as well.
It might be that a save is corrupted or something like it.
Try and rename "Documents/Paradox Interactive/Crusader Kings II/save games" to "Documents/Paradox Interactive/Crusader Kings II/old save games"
See if you can click the tab now. If it works, try and start a game and save, and try to access the tab again.
You can also scan through your old saves and look for something suspicious, I believe a 0 KB size savegame could cause issues like this...