Gnome-sudoku in Edgy fails to run

Binary package hint: gnome-games

Gnome-sudoku: 0.5.0
OS: Ubuntu Edgy Eft 6.10
Linux Kernel: 2.16.17-11-generic

I've installed gnome sudoku with "sudo aptitude install gnome-sudoku"
and the game worked for two days

After a while whenever I click on the launcher, gnome-sudoku doesn't run at all. It simply changes the cursor to waiting pointer, and then "plop!" it disappears. And nothing else happens.

Here is the output on the terminal:

myusername@comp:~$ gnome-sudoku
Traceback (most recent call last):
  File "/usr/games/gnome-sudoku", line 11, in ?
    start_game()
  File "/var/lib/python-support/python2.4/gnome_sudoku/gnome_sudoku.py", line 915, in start_game
    u = UI()
  File "/var/lib/python-support/python2.4/gnome_sudoku/gnome_sudoku.py", line 355, in __init__
    self.sudoku_maker = sudoku_maker.SudokuMaker()
  File "/var/lib/python-support/python2.4/gnome_sudoku/sudoku_maker.py", line 309, in __init__
    self.load()
  File "/var/lib/python-support/python2.4/gnome_sudoku/sudoku_maker.py", line 394, in load
    loaded = pickle.load(ifi)
  File "/usr/lib/python2.4/pickle.py", line 1390, in load
    return Unpickler(file).load()
  File "/usr/lib/python2.4/pickle.py", line 872, in load
    dispatch[key](self)
  File "/usr/lib/python2.4/pickle.py", line 935, in load_int
    val = long(data)
ValueError: invalid literal for long():
myusername@comp:~$