Are you shutting down all non-essential programs (especially anti-virus) before starting the game?
If you start the game and try making multiple saves in a row, does that work better or worse than saves every so often as you are playing? If you can save 4 or 5 times when you first start the game, but only 1 or 2 periodically as you are playing, there may be some kind of memory leak, or something.
Do you have lots of free space on your c: drive?
Not sure what else could cause this...
