I used Mission to cross-class my main character, and I leave Taris as a 6 Scoundrel / 3 Soldier. None of my other characters are cross-classed. I have used the FLU bug to raise a few feats to Master level, and have jacked a lot of my skills super high.
Every time I go to pick my Jedi class, the game freezes, either right as I hit Accept after leveling up, or sometimes before it even loads the level-up screen.
I reloaded all the way back from the Endar Spire and played the whole Taris thing again, and it does the same thing.