Clocktower Mission Crashing

[Doremo]

The Clocktower Mission is becoming quite frustrating. The first time I played the mission, I was saving to a single save slot. After playing on that level for a while, if I save the mission, the game crashes to the desktop and completely erases the saved game. I uninstalled and re-installed the entire game because I had to start all over again anyway. The second time I started saving games into mutiple slots. Good thing because I have played all the missions up to the clocktower mission and the game is erasing the clocktower saved mission again!!! I am at a loss as to what to try. Has anyone else had this problem or know of some cause? Is there a patch for this situation? I would be grateful for any help.